iM 4,1-14,4 Reflow on HD6750M graphics card

[CooperBox]

A colleague mentioned last week that his late 2009 iMac 27" (2.8GHz i7) will no longer boot correctly, seeing graphical artifacts on-screen.
Knowing that the graphics card in many 27" iMac's of this period were reported as defective, (especially this ATI Radeon HD4850), and as he cannot use it as is, doesn't wish to spend any serious money on this almost 9 year old machine. If I knew of a good amateur or a pro who offered a guaranteed reflow service, I would suggest that this would be the most cost-effective - and hopefully long-term solution. However I understand such GPU reflow specialists are a rare breed, and I know nobody, especially in SW France where we're located.
So I offered him my humble services - to remove the graphics card, and rebake in an attempt to reflow the GPU.

I've never done this, but over the last 48hrs have read a great deal about the procedure, and also watched dozens of YT videos - in different languages - and frankly can't wait to get started........
However I'm not too naive to realize that there is a huge difference between theory and practice, although I do claim to be proficient in repairing most Apple PowerBooks, MacBooks, G4 Cubes, and several G3/G4/G5 iMac's.
So, before going any further, I have a number of questions, and would be extremely greatful if Razzerman, Sofad, or anyone else could address the following queries, given that I have no proper reflow station and propose doing this using a domestic cooker (with digital temp display, and low/high fan speeds).

1.My understanding is that on the 2009 27" (iMac11,1 model A1312) the Radeon HD4850 graphics card can be removed without disturbing the motherboard. Confirmation pls? iFixIt doesn't appear too clear on this.
2. Is 200 degrees centigrade (392F) for 10mins considered the optimum 'sweet spot' for baking?
3. Should a liquid flux be applied around/beneath the GPU? If so which one? Would it be a mistake not using a liquid flux?
4. Athough the videos I've watched don't show it, would it not be beneficial to wrap baking foil all around the graphics card, and then cut an opening to expose just the GPU on top and bottom?
5. One apparent sucessful 'baker', put a few copper coins on the GPU, allegedly to add a little weight and assist the process. Is this considered a useful addition to the procedure?
6. On completion, which fan control app would you advise? HDD only, no SSD fitted.
7. Any other 'must-know' tips or tricks?

Finally what are your own experiences in terms of months or years of sucess after such an iMac GPU reflow procedure.

As a footnote, I also have a somewhat similar mid 2010 27" iMac (iMac11.3 model 2.8GH i5) with the Radeon HD5750, which is still performing perfectly (reaches out to touch wood, and caresses the wife on the head) ........
This being one more reason why I'm eager to get started with this, as it will at least be a good learning curve just in case touching my wife's head doesn't turn out to be quite the lucky charm I expected.

 

[casperes1996]

Just to add something you didn't ask for, reflowing is never a long term solution. The solder on these flip chips will break again and it's only a temporary delay.

 

[CooperBox]

Just to add something you didn't ask for, reflowing is never a long term solution. The solder on these flip chips will break again and it's only a temporary delay.

Thanks for the rapid reply. Yes I've understood this.
However, just to play devils's advocate, one could argue that with a machine that is defective and would either be thrown into a closet or sold - albeit with difficulty - as unserviceable at a low price, perhaps one or even two years+ (as some claim) reliable service following reflow could (in my books) be considered a pretty 'long-term' solution for an otherwise useless 9 year old machine.
But I take and appreciate your point.

 

[casperes1996]

However, just to play devils's advocate, one could argue that with a machine that is defective and would either be thrown into a closet or sold - albeit with difficulty - as unserviceable at a low price, perhaps one or even two years+ (as some claim) reliable service following reflow could (in my books) be considered a pretty 'long-term' solution for an otherwise useless 9 year old machine.

Long term in the sense that it adds to the lifespan of a product that would otherwise already be at it's end and has already had a decent lifespan, sure, I get you and agree that it's better than just trashing it

 

[SaSaSushi]

Thanks for the rapid reply. Yes I've understood this.
However, just to play devils's advocate, one could argue that with a machine that is defective and would either be thrown into a closet or sold - albeit with difficulty - as unserviceable at a low price, perhaps one or even two years+ (as some claim) reliable service following reflow could (in my books) be considered a pretty 'long-term' solution for an otherwise useless 9 year old machine.
But I take and appreciate your point.

Most reports I've read for reflowing/reballing are additional months of service, if that and then is heavily dependent on patterns of usage.

 

[Razzerman]

Hello there CooperBox,


Glad to see you're all up for trying this method, and wish you the best of luck. As for your questions:

1) I don't know about the 2009 27" imac model, as to whether the graphics card can be removed, so can't help you there.

2) I personally pre-heated the fan-assisted electric oven to 195C, and baked for 8 minutes in the middle of the oven. I didn't want to overcook the card.

3) No flux applied.

4) I used four rolled up foil balls to keep the card off the baking tray. Try to keep the card as level as possible.

5) The coins kind of make sense - not heard that before though.

6) MacsFanControl for me, and I upped the ODD fan, iirc.

7) Thermal paste on the gpu and some of the surrounding chips, iirc.

Longevity wise, I've had zero trouble from two of the three iMac's I've baked for the last 6 months, and they get used on a daily basis by the kids, playing War Thunder, Elite Dangerous etc. All good so far (touches as much wood as I can see). The third iMac is being kept as a reserve.

Also, take your time and be patient with the imac disassembly - it can be tricky getting everything back in as it came out. I swapped the HD on one of them last week, and noticed a bluetooth or wifi cable had become loose. All good now though.

Very best of luck to you, and gotta love that ZX81

Cheers,

Razzerman

 

[CooperBox]

Hello there CooperBox,


Glad to see you're all up for trying this method, and wish you the best of luck. As for your questions:

1) I don't know about the 2009 27" imac model, as to whether the graphics card can be removed, so can't help you there.

2) I personally pre-heated the fan-assisted electric oven to 195C, and baked for 8 minutes in the middle of the oven. I didn't want to overcook the card.

3) No flux applied.

4) I used four rolled up foil balls to keep the card off the baking tray. Try to keep the card as level as possible.

5) The coins kind of make sense - not heard that before though.

6) MacsFanControl for me, and I upped the ODD fan, iirc.

7) Thermal paste on the gpu and some of the surrounding chips, iirc.

Longevity wise, I've had zero trouble from two of the three iMac's I've baked for the last 6 months, and they get used on a daily basis by the kids, playing War Thunder, Elite Dangerous etc. All good so far (touches as much wood as I can see). The third iMac is being kept as a reserve.

Also, take your time and be patient with the imac disassembly - it can be tricky getting everything back in as it came out. I swapped the HD on one of them last week, and noticed a bluetooth or wifi cable had become loose. All good now though.

Very best of luck to you, and gotta love that ZX81

Cheers,

Razzerman

Hi Razzerman,
Thanks for the reply. I took your comments on board.
Picked up the iMac on Sat, started tear-down the same afternoon, and completed it Sun evening. Could have done it in a quarter of the time, but I particularly enjoy performing tasks of this nature s-l-o-w-l-y and painstakingly to ensure that nothing is missed and the result successful.
This is what the screen typically looked like before rework:-

My following points may help anyone else wishing to perform a similar task:

The iMac glass panel came off easily using one large suction cup, placed centrally at the top of screen. This was purchased in a local hardware store for 1,5euro ($1,2).
Special care was made when removing the LCD display, having read of damage to the sync and other cables attached behind. The most secure position is with the iMac laying on it's back, although with the 8 display securing screws removed, the display when opened will close again under gravity - which makes holding it open with one hand, and detaching the cables behind somewhat more tricky.
I preferred to have the iMac in it's normal (vertical) position. But before removing the last of the 8 screws, I ensured
(i) that the screen was tilted max rearwards,
ii) Then attached 3 strips of masking tape to top of the back panel, one central and two either side.
iii) Then removed the last of the 8 screws
iv) Then carefully prising open the LCD, and with it as far open as possible - without excessively straining any of the cables, attached the 3 remaining ends of the masking tape strips to the top rim of the LCD display. (Make sure that it doesn't come in contact with the glass, otherwise you'll have a potential sticky mess to clean off)!
Now one can work with relative ease using both hands to disconnect the few cables behind.
The masking tape idea is really for 'belt & braces' security, as without it if the lcd display did tilt forward - as it often can without being retained by hand, the top sync ribbon cable could be torn away and rendered scrap. Believe me, it has happened if you read some of the horror stories on-line.
Once the display was removed, I carefully examined and cleaned the removed cables /connectors on the rear - and discovered my first anomaly. Although the top left-hand sync ribbon cable had been carefully disconnected with a light rearwards pull, I noticed that 2 of the 4 gold connectors were folded over - presumably during initial fitment. See photo:

So my first task was to remedy that. Using a good magnifier (width of each gold connector is approx 1mm), after cleaning both surfaces, using the tip of the finest needle I could find, I carefully applied the minutest drop of superglue to the underside of each gold connector in turn, and pressed both back onto the ribbon cable. (I thought - but wasn't sure, that superglue was non-conductive), but ensured nevertheless that the glue did not bridge the gap between the gold connectors). That fix seemed to work.
Before commencing internal tear-down, I'd realised that removing just the graphics card on it's own was relatively easy, but thought why not give this iMac a complete refurbishment by removal of the logic board, all three fans, and give everything a thorough clean, including re-pasting of the CPU.
After that it was pretty routine; methodical detachment of all the connectors, before pulling out the motherboard with graphics card still attached. One of the cooling fans is only accessible once the motherboard is removed. And boy, those fans were crying out to be cleaned, as shown by these photos:




With an air line and a brush these fans cleaned up like brand new!

Once removed, the graphics card was 'baked' for 10mins at 200deg after pre-heating the oven. I had no idea how to switch our oven on, let alone regulate it for temp & time, so being somewhat of a cordon-bleu chef, I left that task to Mme CooperB. (No copper coins were placed on top the GPU, nor did I use any liquid flux). On completion, with the baking tray pulled half-way out, I left the oven door open for at least 1 hr, hopefully to assist uniform heat dissipation.
The card was re-assembled using K4-Pro high thermal conductivity paste on the GPU, and K5-Pro ultra thick paste on the memory chips as a substitute for thermal pads. This new product seems to be getting good press which made it my choice.
After removal of the CPU assy for cleaning, it was re-pasted & re-assembled. This I thought was the ideal time to also replace the PRAM battery (in typical Apple style crazily positioned on the inner face of the motherboard), but I noted the original was a BR2032 cell and not the far more common CR2032. Dimension-wise they are identical but apparently do not have the same chemistry, the BR prefix cell claimed to function satisfactorily up to a superior 85 degrees Celsius.

The following photo shows the last of the 3 clean fans being fitted just prior to the motherboard/graphics card assy reinstall:-

With all connected back up, (and not forgetting to refit the 4 Ram memory sticks), I pressed the power button and held my breath. Bingo! The screen came back to life, and has been running fine since Sunday.



For how long this will last is anyone's guess, but as I immediately installed the MacsFanControl app and tweaked to use the GPU heat sink as temp source, I am fairly confident that it should be good for a number of months. For those who are still interested, I plan to report back here at regular intervals with an update.

 

[Razzerman]

Wow, that is one major teardown and clean up - as well as the reflow! Plus to spot and repair those gold connectors...just wow.

Glad everything is up and running, and it's a good idea to report back here if/when the reflow fails. I'll do the same with my brood.

Congrats again,

Razzerman

 

[CooperBox]

Update:
4 months on and this 27" iMac is still performing perfectly. Would that have been the case if I'd just re-baked the gpu and nothing else? That's anyone's guess. The fact that I repasted the cpu and gpu with K4 and K5 Pro, scaled down the display resolution a notch, and also installed MacFanControl - all of which address heat issues to a certain extent, and hopefully provide belt, braces, safety harness approach and prolong serviceability.

 

[CooperBox]

Thought it may be of interest for some to provide an update here.
I today contacted the owner of this 2009 iMac 27" on which I reflowed the GPU. He told me it functioned for 8 months before failing again with the similar grey/pink striped screen.
This was expected, but what wasn't sure was how long it would remain serviceable. So in short here, the owner benefited from 8 months with an iMac which was otherwise crippled image-wise.
Ok, rather a lot of work to achieve what I set out to do, but no regrets as I learned a lot along the way.
Forgetting re-balling for a moment, would anyone know if there is a long term solution on these iMacs by installing an alternative GPU chip? Anyone had this done?

 

[SaSaSushi]

GPU replacement is always a (difficult) option if you can get the part but it likely won't come cheap for a guaranteed new unit. Welovemacs sells the Radeon 4850 for $429.95.

According to the iFixit GPU replacement guide for the Late 2009 and Mid 2010 iMacs you can also upgrade to the Radeon 6970M used in the 2011 iMacs but it's twice the price.

 

[Fishrrman]

For a 2009 iMac that has failed a second time, it's probably best not to spend a penny more on it.
Time for something new (or at least, "newER")...

 

[Razzerman]

All of mine are still functioning, with one in regular, everyday use. It'll be interesting to see how long it lasts. I have set the ODD fan to a higher setting, making a little more noise than usual, but as the daughter is playing music, it makes no difference.

 

[evanDove]

GPU replacement is always a (difficult) option if you can get the part but it likely won't come cheap for a guaranteed new unit. Welovemacs sells the Radeon 4850 for $429.95.

According to the iFixit GPU replacement guide for the Late 2009 and Mid 2010 iMacs you can also upgrade to the Radeon 6970M used in the 2011 iMacs but it's twice the price.

The Radeon 6970M used in the 2011 iMacs were the subject of a 3-4 year recall by Apple. There were SO many failures, that they replaced the card for 3 years from the purchase date of your computer, and then extended it to 4 years, as not everybody had experienced the failure in the first three years. I ran into a failure after that period and spoke to a senior adviser at Apple to see if they could/would make an exception and replace mine anyway. The rep told me that he/they might be willing to do it, but they no longer had access to those cards at all. (I guess they had all been used for replacements). So, bottom line, replacing the graphics card from the late 2009 27" iMac with the known failure from the 2011 does not seem like a wise choice. I believe the 6970 is a 1TB card. A mac tech here on Maui, Hawaii, said the 512GB card, (from the 2009), could be used, but I also saw something that said it couldn't. All that having been said, I've run across two miid 2011 27" iMacs, with the 6970 card which seem to be running fine. (Maybe they were replaced cards?)

 

[racoop]

A successful cooking of the GPU in my 2011 iMac tonight! I had the original GPU replaced under the extended warranty, and it gave me about 5-6 years before crapping out. Let's see how long it lasts post-baking.

 

[iahsa]

I purchased 2 identical 2011 iMac 27inch machines with all the upgrade options available in July of 2011. The one I used on a daily basis for graphic design and video editing lasted about 4 years before the graphic card died. I know Apple charged my $600 to put a new one in, I didnt know they had a recall program, I just know that the Apple Care had expired and I got charged. I did do a RAM upgrade to 32GB and a WiFi/Bluetooth upgrade after my warranty expired for Hand off and Airdrop capability in my computer only since I did work on my 2011 MacBook Pro 17in that I wanted to swap work with. One Apple returned my GPU repaired computer, the Wifi didnt work. I had to open up my Mac and found they didnt reconnect the cables of my upgraded card. That being said my "New" graphics card lasted until Early 2018, less time than my original card. I again took it to Apple. Again they said it would be $600 to replace the card. I said ok because I really didnt want to buy a new Mac yet. They "ordered" the part then called me a week later and said they would be unable to repair my Mac because it was previously worked on by someone else (me). I told them that the was the case when they repaired it the 1st time (I later found out by my son's friend who worked at the Genius Bar that they actually couldnt get the part and do the repair for the quoted price, so they find a reason not to.) I gave up and purchased an iMac Pro (regretting that now, looking to trade it in). Now my husband's computer (use for light photo editing more on a twice a week basis rather than my daily use) didnt have a GPU problem until 6 months ago, it got green stripes. I was doing research on a repair on my son's 2011 MacBook Air 11in (3rd repair..wifi card went out, I replaced it, display glass cracked when he left a pencil in it and stepped on it..I replaced the glass only...what a pain!) anyway, I kept seeing "baking" videos...I clicked on one and said, wow..I'll try that. If I goof or mess up taking it apart, I have a whole other iMac with parts. So my one of my sons and I tore it down, "baked" the card and low and behold, it worked. I may bring my old iMac out of the closet and see if I can do the same with it. I also did a search to see how the bake lasts and they range from 3 months to 3 years some rebaking up to 3 times and they still work, so what the heck, why not! I upgraded the HDD to a 2TB SSD 32GB RAM and it keeps up pretty well. I have a temp control app, a usb fan (plugged into a wall mounted power strip) that blows heat away from my computers. We shall see how long it lasts. My kids run old Jedi Academy games on my husband's so keeps them off my very expensive iMac Pro. The tear-down of the GPU wasnt as scary as I thought. Those on the fence, go for it, it is almost therapeutic and fun especially if you go in it thinking, its already broken, what could happen?

 

[Steven Mathias]

Just for the information of those trying this , YES it will work 99% of the time but its a quick fix and it will fail again , theres heaps of you-tubes on it , keep the card off the tray , 3 or 4 alloy foil stand off posts will do , bake @ 200 c for 10 mins in a preheated oven , be patient let it cool naturally with the oven door open before removing it , and as a side note on a 2011 imac you DONT need to remove the whole logic board , the gpu can be removed separately with care , there also is a few companies one in Greece and one in the UK that fully refurbish these cards for around $100 USD BUT wont touch a baked card , so if you know your machine has not been baked this route will offer a permanent fix

 

[Christian Bartosik]

a few companies one in Greece and one in the UK that fully refurbish these cards for around $100 USD

Can you please give a link or a hint?

 

[CooperBox]

Just for the record I too would be interested to hear of the UK based company that fully refurbish these cards. Do they guarantee them and if so for how long?

 

[Nguyen Duc Hieu]

Why bother with 3rd-time baked cards?
Purchase a new MXM card (laptop version), flash its BIOS, and you will have a much more powerful yet stable card to use for several years.

2011 iMac Graphics Card Upgrade

iMac 2009 to 2011 MXM3 graphics card upgrade (Lastest update 10/13/2023 - this is the official documentation page - you found it finally!) This is the single and only documentation post. During the last years we constantly updated this post to reflect the lastet development of vBIOS and OCLP...

forums.macrumors.com

 

[CooperBox]

In my post #10 above, I mentioned that after my rebake of the Radeon HD4850 graphics card, the owner benefited from 8 months with a 27" iMac which was otherwise crippled image-wise. He was pleased, but frankly I'd hoped and even expected that it would hold up for longer, especially as I had added belt & braces+ in an attempt to prolong the life, i.e:
i) Used an excellent non-conductive K4-Pro thermal paste for the gpu chip
ii) Used generous amounts of K5-Pro for the other 11 chips on the card
iii) Added & set up Macs Fan Control app.
iv) Scaled down the screen resolution from 2560x1440 to 1920x1080.

When the screen failed after those 8 months use, the owner boxed it up and had forgotten about it until I contacted him and offered to buy it very cheaply for spares, which he agreed to.
Once home this was the typical screen pattern with the defective GPU. (I'm also backing up here in Target Mode).


I again removed the graphics card.




Rebaked it, and re-pasted with K4 and K5 Pro.


One freshly-baked 'Cordon Bleu Maison' HD4850 graphics card.......



And re-assembly to the heat-sink.



With everything re-installed, it booted and immediately sprung back to life. It was then that I observed that despite my recommendations against it, the owner had disabled the Fan Control App, and reverted to the 2560x1440 screen resolution. Whether the card would have had a longer lease of life if my tweeks had not been changed is anyone's guess......
I reset all these tweeks - especially setting the ODD fan to a slightly higher setting in an attempt to give the card an 'easier ride', so time will tell whether this proves to be effective or not.
The original HD was beach-balling far too frequently, so today I removed it to install a new Samsung SSD I had available (whilst shorting out the original HD temp sensor cable to prevent the fans running at max speed). With trim enabled and a fresh install of High Sierra, it's rejuvenation can certainly be felt and appreciated. Again it's a joy to use.

The iMac on completion.


I'd like to think this will give satisfactory service for another year's service or even more. If it doesn't I'll then consider purchasing an MXM card (or another) suitable for flashing. Will also provide an update in due course.

 

[Nguyen Duc Hieu]

If you downclock the GPU a bit, it will last much longer than the 1 year target.
Downclocking GPU will require Windows.

 

[The_Croupier]

I accidentally forgot about my gpu in the oven, it was in for about 30 minutes. Works perfectly, im hoping that the long bake time = longer life span 🙄

 

[casperes1996]

Wonder if Jen-Hsun (CEO of Nvidia) has been following this thread, since he announced GPUs by pulling them out of his oven

 

[CooperBox]

Here's a quick update since my 31st Jan post. And it's good news!
This same iMac has been performing superbly since then so it's still looking quite promising. Sure the detractors will probably say that it's only a matter of time before it fails again - and they may be right, but methinks that my over-generous dabs of K4 and K5-Pro thermal paste for the gpu plus my additional tweeks mentioned are all contributing to extending the life of this 2009 iMac. Mac Fan Control set up manualy shows that the internal temps look fine.
With an SSD and adequate memory these machines are still a joy to use, and it's seen a fair amount of HD YouTube viewing too during this period with the display resolution set/scaled down a notch to 1920x1080.
Check in again next year when I'll provide a further update - whichever way it goes.