iMac Intel 27" EMC 2374, AMD Radeon HD 4850 Videokarte tauschen

Forget it, I deleted AMD drivers from Extensions library and the Mac startup normally. But can't use it because not using the GPU everything is extremely slow. I formatted for nothing :/

Thanks anyway for this great site!!!

Regards from Argentina.

Glad you figured out how to solve your problem, and I wish my video card problem could have been solved your way! :-) But you will know when the video card fails because you will experience random freezes and sometimes you computer won't boot. You will also see strange blocks or other artifacts on screen. You Mac may also not wake from sleep. I experienced all these things and they went away when after I fixed the video card by oven-baking it. Best wishes!

Hi, Joe. I performed the repair in February this year. It is now June. No problems at all during those 3+ months. Keep in mind that I am not the only person who has performed this "oven bake" trick to restore their iMac's video card back to life. The following link is to the YouTuber who was the inspiration for me to try the trick, and he reported in Feb. 2017 that his iMac had been working fine for more than 17 months after his oven bake (which is precisely why I took the time and effort to try it):

https://youtu.be/9vPM41ZmLos

Thank you for your kind words, Dean. I'm very pleased to hear the video card bake worked for you. Buying a new card would probably last longer than the "bake fix" but in my personal experience, it lasts 3 years. Three years after buying my late 2009 iMac, it developed the video card problem. Apple replaced the video card with a new card, but 3 years later the same thing happened. I would assume the same would be true of any new replacement card of the same model. Whether a different model card would fair better is anyone's guess, but keep in mind they may not fit perfectly if you try them, and there could be thermal issues as well if they run hotter than the stock card. Best wishes!

I've read many different reports from people who say their Mac exhibited different things on screen, either artifacts, or totally white or totally black, and sometimes with vertical or horizontal lines. Sometimes there are no screen anomalies but the machine just freezes. In almost every case the culprit is that silly video card. The design of that card is faulty. It would be nice if we could just swap it out for a different card, but the cards that don't appear to have the same fault won't physically fit in the iMac. So we either do the bake resurrection trick or get rid of the Mac and buy a 2015 or later edition. (I have a late 2015 edition 27" 5K iMac at the office and it's very well made -- never had a problem with it -- and it runs cool too.) So even if you "replace" your video card, the same problem will occur 3 or so years down the line. Apple replaced my card 3 years after I had purchased my Mac due to the video card fault, but 3 years later it had the same problem, which is why used the bake.

Keibert, thank you for your comment. I agree that paying someone to reball the GPU chip would probably last a bit longer than the oven bake shown in my video; however, I know from experience that even a brand new replacement video card only lasts about 3 years due to some defect in the design of the card itself. So basically you get 3 years out of a new card, perhaps less out of a reball and a little less, perhaps, with an oven bake. But the cheapest overall solution (costing you nothing but time) is the oven bake. Some people have reported going more than 17 months on the oven bake, so it's not a bad solution for those who want to avoid paying anything.

Reiner, thank you for your comment and question. I have no experience testing a different video card, but I have read that some newer cards from 2010 and 2011 iMacs will function properly in the 2009 iMac. HOWEVER, I have also read that the physical size of those newer cards is not 100% the same as the stock 2009 video card, which means you may need to do a little cutting if you want to put a newer card in your iMac. Another potential downfall is the fact that those newer cards are faster but draw more power and generate more heat as a result. As such, I can only advise replacement with the same video card. And if ever you decide to get a new iMac, the late 2015 and newer 5K models are great. I have a late 2015 5K at the office. It runs cool and fast, with no video card issues to date. Best wishes.

No. I actually did 2 bakes of my video card. After my 1st bake I replaced the thermal paste, but the video card exhibited the same problem 4 months later. If it was the paste, as you surmise, the problem would not have recurred after 4 months. And by the way, after my 2nd bake, the machine is still going strong. I’m into my 5th month of use now. If you open my video in YouTube you will see a link in the description to my 2nd Bake video. Best wishes.

The v-sync ribbon cable you mentioned damaging would not affect the fan speed, so it’s clearly something else. If you forgot to insert any one of the many connectors, or if you inserted one improperly during your reassembly, such could very well cause fans to ramp up. But it would have had to have been one of the connectors pertaining to a temperature sensor. If re-opening your iMac is troublesome (and you and I both know it is), you could opt to just use a software solution to control fan speed. There’s an app named “smcFanControl” which works fairly well. “Macs Fan Control” is yet another app you could consider. But if you simply cannot rest until the root problem is solved, then you will have no choice but to re-open your iMac and check the tiny connectors (those leading to temperature sensors).

You say you cannot see any connector attached to “HDD Temp.” Simply locate your hard drive (upper middle area) and you should then find a pair of wires attached somewhere on the hard drive, which is the temperature sensor. Following that wire pair until you see the disconnected connector dangling somewhere, then reconnect it.

All 2009 iMacs have the temperature/thermal sensor cable attached to the stock HDD. You can see that connector in Step-10 here:

Intel iMac 27" EMC 2309 und 2374 Festplatte wechseln

Mikko, I’m sorry you are having problems after your bake. Because of the complexity of the procedure, any number of things could have gone wrong. For example, it could be that you simply neglected to connect a single connector. Or it could be the video card itself wasn’t secured well enough into it’s socket after your bake. You probably would have noticed if you broke a cable (especially those thin ribbon cables) when you opened the iMac, so it’s probably not that but breaking the ribbon cables can cause a black screen. It’s probably just a loose or missing connection. But the bad news is that you’ll need to remove the display again in order to verify.

Thank you for sharing your experience, Jimmy. I’m pleased to hear the bake worked for you. Removing the motherboard can make it easier to replace the BR2032 PRAM battery, but replacing that isn’t absolutely necessary. You probably wouldn’t get very much if you tried to sell your old Mac, but if you have a family like I do I’m sure you can put it to good use in your home. If not, be sure to donate the machine rather than discarding it. One man’s trash is another’s treasure!

Hi Timmy, yes I have heard stories similar to yours. You definitely have a video card problem and the bake would work for you. Just make sure you follow my instructions, especially about replacement thermal paste. Please also note that I have 2 instructional videos on the subject. The video above (here in iFixIt) shows my first bake which unfortunately lasted only 4 months. I then made another video of my 2nd bake, where I did not remove the entire logic board, and my iMac is still going strong on that bake. On that bake, I changed the type of thermal paste, so perhaps that contributed something positive to the bake repair. Please watch my video above on YouTube, then check the text Description underneath it for the link to my 2nd Bake video. You may also want to read the experiences of others in the Comments on YouTube. I reply to every comment and you’ll find a lot of useful tips and advice there. Best wishes!

You can buy K4 & K5 Pro direct from the company in Greece who makes it:

http://www.computer-systems.gr/content/p...

The round container in the photo on their website looks different from the lip-balm dispenser in the EBAY link you provided for me, but it contains the same thermal compound. Since it was faster and cheaper for me, I used Amazon here in Japan to buy it. For you, either direct from the maker or EBAY will work — whichever you prefer.

Yes, that paste (both kinds, K4 & K5) you linked on EBAY is exactly what I used in my 2nd Bake. And as of today, that 2nd bake has lasted 7 months and the iMac is still being used daily (even for games) without a single problem.

Kevin, it seems that you merely forgot to connect one of the many connectors you disconnected in accordance with my video. I agree that opening your iMac again to find that connector would be troublesome and time consuming. As such, I recommend that you just set your CPU fan to run at a constant speed using Macs Fan Control. To do that, just click “Base sur Ambient” and then a little sheet will drop down, allowing you to choose a “Constant RPM value” (the top-left radio button in that sheet). Minimum is 1200rpm, which should be good enough, but if you want your machine to run cooler, you can bump it to 1500 without increasing the noise too much. Please let me know if this helps.

Thou art welcome, Rajeev! :-) Thank you for telling me of your success. Best wishes to you and your resurrected iMac!

Thank you for your comment. While I agree with you that Apple is sadly using inferior paste, the tragic reality is that your average Macintosh buyer is not equipped to do that themselves, nor are they aware of the need for it. Even so, not all Mac models are afflicted by this video card plague. The fact is that the 2009 through about 2012 (2013 too?) models of iMac used a video card that was not designed well. That combined with subpar default fan speeds contributes to this problem of freezing and video artifacting.

I’ll just finish saving up some money and try it out. If it doesn’t work, illl just sent it back.

Because I do not have first-hand experience with using a video card from a 21.5” iMac in a 27” iMac, I cannot offer you any compatibility guarantees. But assuming you have a ATI Radeon HD 4670 card, be aware it is a very different shape than the ATI Radeon HD 4850 in my late 2009 27” iMac. Just Google those card names, then click on IMAGES and take a look for yourself. Because of the shape difference, the heatsink wouldn’t fit right. And also note the ATI Radeon HD 4670 card only has 256MB of VRAM.

Thank you for your kind words, Carlos. I cannot offer you specific guidance on the heat and duration of using a Heat Gun instead of the oven bake method, simply because I myself have never tried the Heat Gun method and therefore cannot vouch for its successfulness. THEORETICALLY, it very well could be even better than the oven bake as the heat would be localized to the GPU only, rather than the entire card. However, you must be very careful with heat guns as some are hot enough to melt the solder, and when that happens SMD components will start to float around, potential creating more trouble for you than you had originally. The Oven Bake method is only 200°C, which isn’t hot enough to melt even Lead solder, so there are no worries that SMD components will shift out of position. But 200°C is hot enough to repair whatever broken leads there are in the GPU die.

Thank you for your kind words and for letting me know of your successful bake! It marked this job as Difficult because it really does take a long time if you’ve never done it before, and it can be very intimidating for people with no experience whatsoever in dealing with electronics. But as you point out, if you are determined (and have the needed tools too), it is certainly not insurmountable!

Thank you for your comment. Yes, I am well aware of that, and indeed, my 2nd Bake Video clearly shows the process:

https://youtu.be/6BJGLFCigdA

But that doesn’t eliminate the need to remove the motherboard if you wish to (a) replace the BR2032 PRAM battery on the back side of the board, or (2) clean behind the motherboard. But again, I made two videos, so the viewer can choose whichever method suits them. Thanks.

That’s wonderful to hear. Thank you for letting me know. Best wishes to you and your newly resurrected iMac!

UPDATE

iMac is still running - happy user for 15 additional months now :))

btw. I’m using mac’s fan control. So for games I have the fans working quite hard. I was amazed by the heat that is produced. No wonder, having the fan run in normal mode causes trouble in many cases…

Thank you for the 15-month update. I’m so pleased to hear your iMac is still going strong. So is mine. I too am using a software-based fan control app, running all the fans at about 2000rpm. I can hear them in a quiet room, but it’s better to keep the iMac cool inside than to keep the fans running at the stock speed and have something overheat. I’m still unsure if we’ll get more than 3 years out of the bake, seeing that even a brand new card from Apple, installed by Apple, lasted only 3 years in my experience, but who knows. Maybe all those series video cards just needed a little more time to bake before they were released into the wild. :-) Anyway, may your iMac give you many years of life! Best wishes!

UPDATE

still running :))

So thats 3 years now! I’ll keep u updated

I certainly appreciate the regular updates on your video card. Three years is very, very good! Fingers crossed you get another 3!

I believe you have a 2010 iMac? Glad to hear my video was helpful to you. Sorry to hear you were actually sold a 6770 instead of a 6970. Some people have asked me if it’s worthwhile upgrading the video card in the 2009 iMac (which is the one I have). I replied that I myself didn’t want to take the risk that the newer card might be hotter than the old, or that the newer card might not fit perfectly (depending on which newer card was chosen). It’s not simply a matter of fitting the video card but the heatsink as well. Anyway, thank you for letting me know of your success!

Even though you have a 2011 iMac 27” and I have a 2009 model, the symptoms you describe are very similar to what I have seen. So yes, I do think that baking your video card may resolve the problem. It’s very unfortunate that Apple charged you $50 for nothing and made you wait 3 weeks too! That’s just horrible. You said you purchased the supplies needed for the bake, so you are good to go. But please also watch my 2nd Bake video if you haven’t seen it already: https://youtu.be/6BJGLFCigdA

Dear James: Thank you, as you recommended, it worked on our mid-2011 27” iMac!

I watched your videos twice and followed everything you recommended, except I only had the ‘silver’ type paste and not the white one so I kept the ‘white pad type goo’ on (they came off on the ‘non-bake’ part), and smushed it back into shape. I had never opened a computer or electronic device before in my life and yes this wasn’t an easy fix and it took a long time.

One of the fans seems to have gone into overdrive even though computer is not running hot any more. We just keep it on for short times, get the information that we need (we are migrating the data for safekeeping somewhere else) and then turn if off again. After we are done with that we are hoping to use it as a second monitor.

Again, Thank you very much for your valuable service!

Thank you for giving me an update. I’m glad to hear the bake worked for you. As to the fan spinning too fast, that is probably caused by your having forgotten to connect a cable or perhaps you connected it in a way the wires are not making good contact. You could reopen your iMac and search for that cable, or you could just download Macs Fan Control and use that to run your fans at the speed you like.

Since you decided not to replace the white thermal pad goo on the memory chips of the video card, you basically have the same situation as my first bake. I added a bit of thermal paste on top of that stock goo, but my 1st bake lasted only 4 months and the artifacts and freezing returned. After my 2nd bake, I cleaned off all the good and used K5 Pro on the memory chips, and K4 Pro on the GPU. So far, my 2nd bake has lasted 1 year and 6 months. For now, enjoy your newly resurrected iMac!

As it turns out I reassembled the iMac; did not repair or replace the heat sink sensor and did not connect it to the MoBo.

The Mac started up completely. Before I baked the GPU, it would stall with the startup progress bar exactly halfway. It would start ok in Safe Mode.

Robert, thank you for your two replies. You really need to fix that sensor before you start using your machine full time. Can you shoot me a clear, zoomed in photo and post it to Flickr or DropBox or CloudApp, etc. and then post a link to that photo here so I can see it? That way I can better informed you about how to repair it. Thanks.

Most other cards won’t be a perfect fit, even if they work. Newer cards may also run hotter, which is not something I can recommend. Beyond that, I cannot say much more because I do not have first-hand experience with using a non-standard card. If you want to be 100% worry free, stick with the 4850.

I’m so happy to hear of your resurrection success! Best wishes to you and your revived iMac!

Thank you for reporting your success story, Brad. To clarify, you performed your very first video card bake (at 400°F/200°C for 9-10 min.) 13 months ago and recently your Mac showed the same video card failure symptoms again, prompting you to perform a second bake? If so, what thermal paste did you use on your first and second bakes? I ask because my first bake lasted only 4 months, and that might have been due to the very old thermal paste I used, and the fact I didn’t clean off all of Apple’s stock thermal pads which cool the video memory chips. But on my second bake, which has thus far lasted more than 14 months of daily use, I used K4 Pro and K5 Pro (from Greece, not electrically conductive) and I believe that has made a positive difference. Best wishes.

Hi James, i used a fairly generic thermal paste; silver containing for the main chip and a non conductive for the side chips/blocks. The bake was at 200 for 9 mins. the recent failure was exactly the same as the first (two horizontal pink bands across the screen, and failure to boot). My usage is pretty light, so will see how we go this time!

That sounds similar to my first bake. I used an old tube of Arctic Silver V on the GPU and an old, generic, previously unopened, non-conductive paste on the memory chips. But again, I didn’t clean off the old thermal pads that were on the memory chips and just applied that non-conductive paste over the remaining pads. After my 2nd bake I did a thorough cleaning of all the thermal paste material, and then I used freshly opened and new K4 Pro on the GPU and K5 Pro on the memory chips (which is a thick paste that acts as a replacement for thermal pads). Not sure if my first bake lasted because I didn’t clean off the old Apple pads on the memory chips, or if the GPU simply needed two bakes to finally come back to life. But as I said, I’ve gotten about 15 months on my 2nd bake, and that is with daily use of the machine, including GPU intensive games by my son. I also use smcfancontrol to keep the fan speed higher than stock. Best wishes to you and your twice-baked iMac!

A Quick update for those keeping track… 4 months after my second bake i have had another failure lets see how the third attempt goes. this time, i put the chip in the over cold, then let it warm up to 200, then in for the 9/10 mins at temperature, then turned off the heat, and let it sit and slowly cool down over an hr or so. my thought is that the slow heating and cooling should allow ample time for the solder to anneal. anyone else had multiple attempts out there? thanks

Brad, when I previously asked you what kind of paste you used on your 1st and 2nd bakes, you replied by saying, “a fairly generic thermal paste; silver containing for the main chip and a non conductive for the side chips/blocks.” Since your 2nd bake lasted only 4 months, I would strongly suggest you use different thermal paste. Indeed, I think it would be worthwhile for you to purchase the same paste that I did — K4 and K5 Pro. That paste has lasted more than 1 year and 7 months so far. And it was on my 1st bake that I used inferior paste which resulted in an only 4 month life for that bake. I really think paste matters just as much if not more than the temperature and duration of the bake.

Thanks for the advice James. i will track some down for the next time it goes. You mentioned K4 and K5; is that K4 on the side blocks, and K5 on the main chip? as a side note, i was running the same software the last two times it went (citrix receiver to connect to my work network). I might have to stop working after hours!

And again, thanks for the great video; i think without this i wouldn’t have had confidence to try the bake first time around!

K5 Pro is the gummy thermal pad replacement for the memory chips on the iMac video card, whereas K4 Pro is the traditional style liquidy thermal paste that is intended for the GPU. Neither is electrically conductive so spill-over is a non-issue. But it’s important not to confuse them. When you see them with your eyes, you cannot confuse them because they look and feel so different. But when discussing the part numbers, it’s easy to confuse them. Thank you for sharing your story. May your iMac continue to have a long and happy life, Brad!

Simone, thank you for your kind words. As you so correctly and eloquently put it, the 2009 and newer iMac is indeed both “ridiculous” and “infuriating” in terms of its design. And that is why I had to list this repair as being “Difficult.” Nevertheless, many people have chosen to proceed with the repair, and the vast majority of people who have commented about their experience have reported success. It is wonderful that you were blessed with 9 years of use before the problem happened though. That does give me a little hope the bake will last longer than 3 years. In my mind, it’s 3 years because that’s how long my first video card lasted, and that’s how long an Apple replacement (brand new card) lasted. But maybe the bake makes an old card better than new. Let us hope so! Thank you for your comments. I will make changes accordingly! I wish you a wonderful holiday season, Simone!

I would recommend against using a different video card for 2 reasons: (1) increased heat, and (2) slightly different size. I’ve read that some people put in a newer card (pulled from a new iMac) into the 2009 iMac with “minor cutting.” But cutting was involved. These Macs get hot enough as it is, so adding more heat from a more powerful card probably would not bode well for the iMac. That’s what led me to bake my stock card back to life. My iMac is still going strong, so if the stock card is adequate, I feel it’s worthwhile to do the bake.

Thank you for letting me know, Thomas! I’m pleased to hear it worked for you. And yes, I agree that temperature sensor connector is a bother! Best wishes!

If you don’t change the BR2032 battery, you do NOT need to remove the entire logic board. This is mentioned and shown in my SECOND VIDEO, the link to which I posted above in the Introduction. Please be sure to watch that video on YouTube where you can see my detailed text description under the video which contains lots of useful information.

I assume you purchased the K4 Pro and K5 Pro thermal paste set? I know those work, so I highly recommend them.

Don’t forget that you can do the job without removing the entire motherboard, as per my second video linked in the Introduction section above. But doing so prevents you from changing the BR2032 battery, which Apple foolishing put on the BACK side of the motherboard where it is ridiculously difficult to access without removing the motherboard at least in part.

Use a regular kitchen oven. Do not use a toaster oven. My oven is a convection type that has a fan and exhaust system, however a normal oven without the fan will work fine. Just ensure you get the temperature correct and bake it for 10 minutes give or take a minute. Use pieces of foil to raise the card a bit so hot air can get under the card. This is shown in my video. Good luck!

The difference between K4 and K5 Pro is huge, so don’t mix them up or just get one. K5 Pro is only when you have a gap between the chips and heatsink that otherwise would require a thermal “pad.” Thermal pads never transfer as much heat as thermal paste because regular thermal paste is applied as a very thin layer and requires the heatsink to make contact with the chip. So if you were to use K5 Pro on the GPU, it would not transfer as much heat as K4 Pro, even if you used a very thin layer of K5 Pro. K5 Pro is specially made for large gaps between the chips and heatsink. For more details, you will need to contact the manufacturer of those pastes.

Glad to hear you could find parts on EBAY Germany. No doubt they came from the same source in China I used to get replacement cables for my 2nd bake. (I used AliExpress to buy direct from China.)

After you get everything put back together, please report back on how well your iMac works. Thanks.

You are the first person who has done the bake at such a low temperature. 275°F is 135°C. Normally, the bake is done at 200°C/400°F. Because your bake is unique, I would certainly appreciate hearing from you every few months during your first year of use after your bake (either in the iFixIt comments or in the comments under my YouTube video). I’m curious if low-temp bakes last as long as the normal temp bakes. In any case, I would recommend High Sierra for the iMac you have. Even though I use a late 2015 5K iMac at the office which supports Mojave, I still run High Sierra on it. Why? Because with each OS update, performance takes a slight hit. And the older the Mac, the more you might notice that speed hit. Another reason I’ve not updated to Mojave on my 5K iMac is because Dark Mode is really the only semi-compelling feature, and I can honestly live without it. Anyway, best wishes to you on your newly resurrected $80 iMac!!

Thank you for sharing details of your experience. And congratulations on your new the resurrected iMac. I’m sure the information you provided will be helpful to others who are reading through the comments. And I must agree that getting some of the connectors properly fitted back into their sockets was a bit of a challenge.

Well, July 2022 and the iMac is acting up again. Embarking on the second bake. Not a bad run with the first time so hopeful it will work as well this time.

You got just under 3 years from your first bake, it seems, which is quite good in light of the fact the bake doesn't offer a permanent fix for the flaw inherent to the GPU chip. Even when I had Apple replace my GPU card with a brand new and official replacement card, it too died about 3 years later. At some point the re-bakes will stop working, as was true of my card (3rd & 4th bakes lasted only 1 week). I then decided to buy a 6970M with triple heat-pipe heatsink, and after a repaste it started working well and still works well to this very day. More about that here: https://youtu.be/9dPsH1zIQMs

I also wanted to suggest that the tools section of this guide should include a Torx T9 screwdriver, as the video mentions there are some T9 screws to remove. In a pinch, I was able to use the small flathead tool on my Leatherman and it was just the right size to loosen a T9 screw. Thanks again.

Jon, I’m sorry to hear of your USB issues. Before I get into that, please note this iFixit page lists the Torx T10 tool you need. A T9 will work, although not as perfectly as the T10. Now as to USAB, the simple answer is you forgot to reconnect one of the connectors when putting it all back together. Or maybe you yanked it out by accident and didn’t notice. It also could be you yanked a wire out from its connector but didn’t notice, which means that even if the connector was put back properly, if that wire is yanked out or making a bad connection, USB and BlueTooth and other features could go down. Another possibility is that you shorted something, which would be quite bad. But I think it is a connector and wire issue. So I am sorry to say that you will need to re-open your iMac, remove the display, and painstakingly check all the connectors again. I have little doubt you will find the culprit that way. After that, please report back with whether it worked or not for you.

Hi James, thank you for the quick response. I did have and use a Torx T10 screwdriver, but I encountered a couple screws while removing the video card heat sink that were T9. I found that both sizes were needed for this repair.

I didn't remove the logic board or any connectors except the display connectors on the first attempt at doing this. I closely reviewed all of the connectors and made sure everything was snug, and reseated one connector labeled RMT IO that looked slightly loose. There was no improvement in keyboard/mouse behavior, unfortunately.

I then proceeded to remove the logic board, replace the battery (in case the NVRAM was somehow corrupt and preventing the keyboard from working), remove and reseat all connectors and the logic board, and that didn't help either.

I did vacuum some of the dust from inside the iMac, so my best guess at this point is that it shorted something out or inadvertently removed a critical component. I was only one month away from getting ten years of use out of this computer.

Vasil, my 2009 iMac doesn't respond to keyboard or mouse anymore after this procedure, so I'm planning on sending it to Apple for recycling. Let me know if you'd like for me to send you my HD 4850 video card which appears to work fine after the repair. Also you may want to double-check that the connectors are reconnected properly. I know on mine that the Displayport cable didn't seem firmly connected. Hope this helps.

Vasil,

What kind of problems did you have before you baked your video card? Also, how are you able to “start“ (boot?) your computer and confirm proper operation if you didn’t have the video card installed at all? That seems rather odd. Before you baked your video card, did you clean off all of the old thermal paste? And did you bake it for 10 minutes at 200°C and confirm that temperature was correct? And what kind of thermal paste did you apply after your bake?

@Jon Yes i checked every connector several times and still nothing. I believe that my card is dead. It will be great if you can send to me your 4850 video card ^^

@jabbott0 Please email me - dominatorpc@tutanota.com for the card . Thank you in advance mate.

@jdw1 I replyed back in the comment section on youtube :) Yes i cleaned the old thermal paste then baked for 10 mins at 200 C not more then applied a new one thermal paste ARCTIC

Vasil, I’ve been replying back to you (OfficialDjNaijal) in the comment section on YouTube. And as I said there, LED1 and LED2 refer to the power supply, not the video card. So you very well could have a power supply problem, or something is being short-circuited on the motherboard or on the video card to cause a power related problem.

You also told me on YouTube that something fell off during your bake and you had to re-solder it, and then you showed me a picture, but that picture has three red lines on it and so I can’t see what part you resoldered. It very well could be that component is your problem, especially if it is causing an electrical short-circuit.

If your problem is restricted to the video card alone, then yes, replacing that video card should solve the problem. But if your problem is power supply related, then replacing the video card would not solve that problem.

Kurt, when you say “second time” do you mean “second bake”? I myself had to use 2 bakes before my video card was happy. So far, my 2nd bake has been going strong for 2 years and almost 4 months.

Thank you for your question. I don’t know if the 2008 iMac video cards have the same problem as the 2009. Because of that, I cannot guarantee that baking your video card in the oven with solve the problem. But honestly, I don’t think you have anything to lose since it sounds like the main problem you’re having is with the video card. If you bake your video card and it still doesn’t work, then you would still be in the same situation as you are in now, in need of a replacement video card. The only thing you would lose is some of your time.

Yes, you are right. I will try it, and see how it goes. This machine has been capable of doing all the daily work for me for so much time, I’d like to keep it going for as much as I can. It is a great computer, that still runs decently. If I have new, I will post here. Thank you.

Thank you for letting me know your success, Nelson! Best wishes!

Thank you for your kind comments and for making time to let me know your story of success! Best wishes to you and your newly resurrected iMac this new year!

That’s great to hear Zesstra. Thank you for letting me know your success. By the way, what replacement paste did you apply to your GPU and then to your memory chips after your bake? If K4 & K5 Pro, I believe all will be well. Or if you used K5 Pro on the memory chips and another good CPU/GPU paste like Thermal Grizzly Kryonaut or MX-4 on the GPU, you will also be fine. Some people have used Arctic Silver V (myself included on my 1st bake) on the video card’s GPU, but the problem with that paste is that spill-over will touch the surrounding SMD capacitors, and since Arctic Silver V is electrically capacitive, it most likely will cause problems down the line. You don’t have that problem with K4 Pro, Kryonaut or MX-4 pastes, and of course K5 Pro doesn’t have that problem either. Best wishes!

That’s really great to hear, Will! Thank you for making time to let me know!

Great job, Brad. Thank you for making time to let me know. Feel free to keep me informed here or on YouTube as to the status of your video card over time. Some people who have baked their card are going on 3 years of life now, as per YouTube comments!

I take it you baked it a 2nd time at the correct 400°F (392°F, actually), which is required for the bake to work long term. Thank you for sharing your story! Best wishes to you and your newly resurrected iMac!

Yes, I waited for it to cool then put it in for 10 minutes at 400 degrees Fahrenheit.

Baking it twice like that isn’t a problem. Very glad to hear you got it up and running!

Thank you for sharing your story of success with the 6779M in your 2011 iMac! Please feel free to leave an update in the future as to how your video card is doing over time, either in the comments section here or on my YouTube channel. Best wishes!

Veronica, it truly warms my hear to hear you say that. What a wonderful success story!

Of course, like with a brand new card, the bake will not last forever; but it usually lasts long enough to have made the time and effort required worth it. And at some point multiple bakes may fail you, as was the case with my 4850 card. I replaced my 4850 with a 6970M, and that new card is still going strong.

It is quite unfortunate these edition cards have a GPU defect. If there was no defect, we wouldn’t even be having this conversation. But thankfully there is that strange and odd way of resurrecting the defective cards at least for a time.

Honestly, as an electrical engineer, baking the card is highly unconventional, but you’ve got nothing to lose and find that it does really work, well, you can’t argue against those results.

Best wishes to you and your newly resurrected sweet dinosaur. I’m sure he loves you for loving him! :-)

Four years of life for a bake is the longest duration I’ve heard so far! Bravo! I truly hope your second bake gives you the same! Best wishes.

La pasta térmica marca una gran diferencia en la longevidad. Asegúrese de limpiar toda la pasta térmica anterior antes de aplicar la nueva. También le recomiendo que use una aplicación de software de control de velocidad del ventilador para aumentar la velocidad de sus ventiladores y mantener la máquina funcionando a menor temperatura. Con suerte, este consejo ayudará a que su tarjeta gráfica dure más de 2 meses.

Hi Curtis,

Thank you for your kind words. I only got 4 months from my 1st bake, mostly likely due to my inadequate thermal paste job. But I got 2 years and 9 months of life from my 2nd bake. Unfortunately, the bake can only be used a finite number of times, which is why my 3rd and 4th bake attempts only lasted 1 week each. I then realized I could no longer bake the 4850 card back to life, so I decided to buy the 6970M since I don’t have a Windows PC to flash various Nvidia MXM cards that some people say will work. The 6970M I purchased was used and had a bad thermal paste job, but after repasting it and turning the internal fans up to 2000rpm, it runs stable, and I am still using the 6970M card without issue. You do have to cut some plastic inside the iMac with a box cutter to fit the 6970M’s larger heatsink, but if you following my 6970M video, it’s not too hard. Even so, it’s cheaper overall to try to bake your 4850 card back to life. https://youtu.be/9dPsH1zIQMs

Thanks James. I just watched your videos, and boy do you do a good job explaining everything in such great detail and clarity. I’ll be careful with the display ribbons as well. I’ll try baking my current GPU before buying another one. I just need my machine to hold out until Apple announces a new 27-inch iMac.

Good lock to you, Curtis. The M1 or M2 iMac probably won’t be out until summer 2022, but when it hits, it will be a very attractive machine. If the bake works for you, it should last at least from now until then, if not a lot longer. Best wishes!

That's great to hear. Thermal paste manufacturer's suggest you replace the paste after about 1 year, so while it still may be unsolidified in the tube, it's probably best to replace it for optimal performance. The K5 Pro does come thicker at times. I've bought a couple different batches and found that to be true. But so long as the manufactured date isn't more than 1 year in the paste, it should be fine. You can try squirting some out on a clean piece of plastic and then try to mix it up with a toothpick to see if that helps make it easier to apply.

I'm terribly sorry I did not see your question until now. I don't use or advise use of thermal pads. Instead use K5 Pro paste. It's a replacement for thermal pads which works better because you don't need to measure anything. Follow my video to apply it. Any excess squeezes out and isn't a problem at all.

That's great to hear, Dimitrios! My first bake lasted only 4 months, but my 2nd bake lasted 2 years and 9 months. Please followup in the future to let me know how long your bake lasts.

That's great to hear, Joost! Thank you for making time to let me know your bake was a success. Best wishes to you and your newly resurrected iMac!