27” iMacs, late-2009 & mid-2011: Cannibalize one to save the other?

[Quondam2009]

I posted before that I had managed to bring a late-2009 iMac back to life after a thorough dust clean-out and system update, in the thread 'Brought a 2009 iMac back to life - now what?'
https://forums.macrumors.com/threads/brought-a-2009-imac-back-to-life-now-what.2296404/

Sadly, that didn’t last for very long. After about 2 weeks, the graphic glitches slowly returned until the screen was scrambled, so I had to abandon the project for the time being.

Now however, an new opportunity has come up. My son’s mid-2011 iMac finally started to malfunction (it had random shutdowns of increasing frequency), so he got a newer iMac to replace it.

So I now have two broken iMacs for a repair project:

iMac (27-inch, Late 2009)​

2.66 GHz Intel Core i5​

4 GB 1067 MHz DDR3​

ATI Radeon HD 4850 512 MB​

(Malfunctioning GPU and Superdrive)​

​

iMac (27-inch, Mid 2011)​

2.7 GHz Intel Core i5​

4 GB 1333 MHz DDR3​

AMD Radeon HD 6770M 512 MB​

(512 GB SSD replacement and functioning GPU and Superdrive, but random shutdowns)​

The 2009 iMac has a malfunctioning GPU and Superdrive. The Apple Hardware Test revealed no errors, and Etrecheck revealed no major issues.

The 2011 iMac has random shutdowns. The AHT shows no issues on the shorter test (I cannot run the longer test, because the computer shuts down during the extended memory test). The system logs show no kernal panics, but searching the logs using:

log show --predicate 'eventMessage contains "Previous shutdown cause"' --last 24h

shows the dreaded message:

(AppleSMC) Previous shutdown cause: -128

I call it dreaded, because the shutdown code chart I found says that the cause is “Unknown”, and every similar thread in MacRumors that I can find just ends with the issue not being resolved.

There are some things I can tell about the 2011 iMac’s issue:

• The shutdowns are sometimes a random restart, or sometimes a complete shutdown. Sometimes the shutdown requires an SMC reset (unplugging/plugging it) for it even to start again.
• The issue is probably not the graphics card, because the error also happens during the AHT, which does not use graphics acceleration while it is running. Also the GPU board is a replacement added during Apple’s free service program for the GPU issue, so should be newer.
• The issue may be related to overheating. MacFansControl shows CPU temperatures that bounce around even at idle, and I’m concerned that the CPU heatsink temp runs about 7-10 degrees C below the average CPU temp, when I’d expect it to be about 2-3 C lower.
• There may also be problems with the Wi-Fi and Bluetooth on the 2011 iMac, or so my son claims. i have noticed the wireless mouse sometimes disconnects for a few moments, when it did not on the 2009 iMac.
• Unlike the 2009 iMac that has been sitting unplugged since about 2016, the 2011 iMac has been heavily used daily until about last week. I think my son has run it into the ground without maintenance.

I’m planning to try some repairs on these computers and get at least one of them running. Here are some of my options:

1. Remove the 2009 iMac’s GPU card and bake it to try to re-ball the solder joints. The GPU would occasionally work for a while when the iMac was running hot, but start malfunctioning as it cooled down. That means it might be borderline and baking it might resolve that for a while.
2. Try to troubleshoot & fix the 2011 iMac. I could try some simple maintenance, like checking for packed dust behind the logic board, replacing the thermal paste on the CPU, and replacing the PRAM battery. Possibly cannibalize some identical working parts (like the Wi-Fi card or PSU board) from the 2009 iMac to try to fix it.
3. Fix the 2009 iMac by cannibalizing the 2011 iMac’s GPU board, SSD upgrade and Superdrive, since I’m reasonably sure those parts are all in working order.

Of the three options, I think the third is the most likely to succeed. I believe the 6770M card will work fine in the 2009 iMac (I remember reading that it will work somewhere), and the other parts should be compatible.

Sadly, I’d have to give up the 2011 iMac to do that, and I’d prefer to have that one to hobby around with instead. But I don’t know exactly what’s wrong with it (and there may be multiple issues), and I think I have a pretty low chance of fixing that one.

Either way, I just want a browsing / media playing / hobby project computer, and I don’t want to spend much money on it at all. (I’d rather save that cash for an M1 mac later.)

What are your thoughts/recommendations? Which option(s) do you think I should take? Any suggestions on the cause of the 2011 iMac’s shutdown issue?

 

[Nguyen Duc Hieu]

You can save/repair both machine.

1. Repair the 2009 iMac first, as it is easier and you can use the parts from the iMac 2011, like number 3. Also remove all the RAM and SSD from iMac 2011 and put them to iMac 2009. 8GB of RAM is the minimum to keep the OS from caching on the SSD too much.

2. The GPU 6770m is prone to over-heat failure, too. In the near future you would have to replace it anyway.

3. You need more RAM (use old RAM is OK) for both machine. If you can salvage some from old laptops of yours or your friends, it's time to use them. I prefer 16GB of RAM on my machine.

4. You can try thorough cleaning of the 2011 iMac, and on re-assembling, remember to plug in all thermal sensors.

5. It's time to research for better GPUs for both iMacs, you can save the iMac 2011 with a better GPU.

 

[mdgm]

The 2009 can be used with Target Display Mode with more Macs, I think, but obviously the 2011 has a much powerful CPU and also has a Thunderbolt port so if fixable it will be a much better machine in every other respect. Even with Thunderbolt 1 port though not cheap you can set things up to get speeds exceeding that of a single internal SATA SSD booting off a NVMe drive.

 

[Quondam2009]

I am thinking now that both iMacs can be repaired, as they are both in a semi-working state.

I think I’ll focus on getting the 2009 iMac working first, as Nguyen suggests. I might even be able to do that this weekend, as it is just parts swaps.

I didn’t realize the 2011’s RAM could be moved to the 2009. They both are DDR RAM, but I thought the higher speed would make it incompatible.

I do have the idea that I could use the 2009 iMac as a display for an M1 Mac Mini later, by using the DisplayPort. That would be a bonus for getting that one working, I think.

 

[Quondam2009]

I think I found the cause of the 2011 iMac's problems: A failing Power Supply Unit.

Today, before I went to all the trouble of moving the SSD, Superdrive, GPU, and memory from the 2011 iMac to the 2009, I researched the random shutdown issue online, and found one common cause was the PSU. So I swapped the PSUs between the two computers (they were identical, down to the revision number).

I ran the Apple Hardware Test on the 2011 iMac, and for once it managed to get all the way through the extended test!

So now, I'm running the 2011 iMac for a few days to see if the shutdowns start again. So far, the only issue I can find is that the Wi-Fi is not connecting, which might just be because it is too far from the router. That's not a issue, because I have it connected to Ethernet.

I'm also keeping an eye on the temperatures. The below image is while just having a few browser windows open and a video playing in the background. The PSU in particular is running much cooler than before.

I'll observe this iMac for a few days, and if no problems come up, I'll order a new PRAM battery, some thermal paste for the CPU heatsink (it's probably overdue for replacement) and more RAM.

I may work on the 2009 iMac more later; but for now, it's spare parts, unless there's more trouble with the 2011.

 

[mdgm]

If you find the 2011 iMac to be stable with the PSU swapped in you could use Open Core Legacy Patcher and use the beta Terascale 2 patches to run macOS Big Sur 11.4 if you want. There is lots of info in the macOS 11 Big Sur on Unsupported Macs Thread

 

[Nguyen Duc Hieu]

I think I found the cause of the 2011 iMac's problems: A failing Power Supply Unit.

I'll observe this iMac for a few days, and if no problems come up, I'll order a new PRAM battery, some thermal paste for the CPU heatsink (it's probably overdue for replacement) and more RAM.

I may work on the 2009 iMac more later; but for now, it's spare parts, unless there's more trouble with the 2011.

Great, very well detailed example on the issue. It will be a great reference for me in the future,should my iMac got the same issue.

 

[Quondam2009]

Great, very well detailed example on the issue. It will be a great reference for me in the future, should my iMac got the same issue.

Sadly, it turns out the PSU wasn't quite the problem after all; the next day after I wrote my previous entry, it suddenly shut down AGAIN. This time I was prepared to swap the graphics card, and I didn't look forward to doing it because that would requires removing the entire logic board on both computers.

(Absolutely get the Apple Technician Guide for the iMac take-apart instructions. It saved me a lot of headaches.)

When I went to remove the DIMMs, I discovered there was a LOT of dust packed into the memory card well -- I didn't check there the first time I blew the iMac out. It was packed pretty well into the slots and some of it was a slightly brownish color, like maybe it had gotten very hot.

I theorized that maybe the dust in the DIMM slots was shorting and causing the shutdowns. I very carefully picked all of the dust out with the tip of a hobby blade. Blowing it out wouldn't work -- it was too tightly packed. I cleaned any remaining dust off the back of the logic board (a lot of dust had accumulated there, especially around the solder pins opposite where the DIMMs attach).

I then reassembled the 2011 iMac (and I'm amazed it's somehow able to run after my fumbling). I'm currently using it to see if the random shutdown occurs again. If it doesn't, I'm happy. If it does, then I got enough experience to be confident in transferring the graphics card over the the 2009 iMac.

 

[Nguyen Duc Hieu]

So it wasn't a "thorough dust clean-out" as you described....
I used to imagine a "thorough dust clean-out" to be a complex process which includes disassembling every single part before actually dusting each of them.

 

[Quondam2009]

So it wasn't a "thorough dust clean-out" as you described.... […]

Ha-ha, true that. I really didn’t want to go to the hassle of completely removing that logic board. It was the computer equivalent of not vacuuming behind the sofa.

I’m still hoping that last bit of dust is the ultimate cause of the shutdowns.

 

[unclemiltie]

If there's that much dust I'd take it apart again and make sure you clean out the fins on the heat sinks for the GPU and CPU as well as all of the fans. This will require taking the logic board out. They do pick up a lot of dust over the years and remember that machine is now 10 years old. (mine was a dusty mess when the GPU failed, I replaced it with a K3100M following the instructions here)

Get yourself a copy of Macs Fan Control and look at all of the temp sensors. if the excess dust is causing overheating you'll see the temps rising until the shutdown.

 

[Quondam2009]

If there's that much dust I'd take it apart again and make sure you clean out the fins on the heat sinks for the GPU and CPU as well as all of the fans. This will require taking the logic board out. They do pick up a lot of dust over the years and remember that machine is now 10 years old. (mine was a dusty mess when the GPU failed, I replaced it with a K3100M following the instructions here)

Get yourself a copy of Macs Fan Control and look at all of the temp sensors. if the excess dust is causing overheating you'll see the temps rising until the shutdown.

Yeah, I went completely over the logic board once I had it out, including the heat sinks. I blew it off completely and carefully brushed out any stubborn dust. I used a natural hair brush instead of synthetic fiber to clean it-- but I don't know if that would reduce the chance of static electricity damage.

MacsFanControl is about the first thing I installed when I reformatted the drive, and have been watching it carefully. I haven't observed temp spikes before the shutdowns yet.

 

[unclemiltie]

did you clean the fans?

 

[Quondam2009]

The 2011 iMac is still having the random shutdowns. I left it running with a regularly refreshed browser page open, and it shut down after 3-4 hours, both while in safe mode and while not. I’m making a not-unreasonable assumption that if it happens in safe mode, there’s a good chance the GPU is not causing it.

So I’ve resolved myself to my original plan (3) of transferring the SSD, GPU and ODD from the 2011 iMac to the 2009 iMac. I’ll do that over the weekend, I think.

Since that involves removing the logic boards, I’ll do a more complete teardown, inspection and cleaning on both computers this time.

did you clean the fans?

On the first cleanout, yes. It’s amazing how much dust can build up between the blades. The ODD fan was nearly completely blocked at that time.

 

[Nguyen Duc Hieu]

The 2011 iMac is still having the random shutdowns. I left it running with a regularly refreshed browser page open, and it shut down after 3-4 hours, both while in safe mode and while not. I’m making a not-unreasonable assumption that if it happens in safe mode, there’s a good chance the GPU is not causing it.

So I’ve resolved myself to my original plan (3) of transferring the SSD, GPU and ODD from the 2011 iMac to the 2009 iMac. I’ll do that over the weekend, I think.

Since that involves removing the logic boards, I’ll do a more complete teardown, inspection and cleaning on both computers this time.

There are good chance that a bad RAM module is causing your issues.

Try the RAM on iMac 2009 to see if you can reproduce the issues there.

 

[Quondam2009]

There are good chance that a bad RAM module is causing your issues.

Try the RAM on iMac 2009 to see if you can reproduce the issues there.

That is a good idea. I’ve replaced the RAM on the 2009 with the 2011 RAM, and it‘s running in safe mode now. I’ll know if that’s the problem in a few hours.

 

[Quondam2009]

That is a good idea. I’ve replaced the RAM on the 2009 with the 2011 RAM, and it‘s running in safe mode now. I’ll know if that’s the problem in a few hours.

14 hours later, and no crash. RAM appears to be okay. I think that the most likely cause now is the logic board, followed by the GPU.

Would a failing PRAM battery cause these issues?

 

[Quondam2009]

Well, I've moved the GPU and other component over to the late-2009 iMac today, and I'm currently typing on this post on it. It's too soon to call it a success -- we have to wait to see if it shuts down -- but so far, so good.

One thing I did during the rebuild was to take the temp sensor from the broken optical disk and put it on the SSD, since the SSD didn't have a temp sensor of its own. (Or rather, I was using OWC's SATA adapter w/ the temp sensor on the mid-2011 iMac, which won't work on the late-2009 one.)

I'm going to have to dive back into the computer anyway. Macs Fan Control shows the Platform Controller Hub Die is at 59°, which indicates I didn't plug it in properly, and the GPU temp shows "-". Maybe the app isn't expecting a different GPU? There's also a slight gap at the top of the LCD glass, which likely means there's a cable I didn't fit into a channel properly. And I have to shift the logic board up a half-mm to line up the USB ports with the case better.

First, I'm going to let it run for a while before I open it again, to see if any problems pop up. So far, so good!

 

[Quondam2009]

I’ve run the late-2009 iMac for several days, and it’s been running High Sierra without a hitch. No overheating, no graphics glitches, no sudden shutdowns. The SSD and extra 4 GB of RAM have made it run much more efficiently. I even got to try importing a few more audio CDs into my iTunes library on the SuperDrive!

When FreeGeek eventually opens their physical storefront again, I’ll head over to see if there might be more RAM to pick up, or other older hardware to add.

My future plans for these machines (assuming this works out) are:

1. Try setting up external storage, maybe Firewire 800 or a networked drive. Anything faster than the very slow drive I’m using for Time Machine backups.
2. Try to get the mid-2011 iMac to stop crashing. My current theory, based on the CPU & heat sink temperature difference, is that the thermal paste connecting the two has deteriorated and the CPUs are overheating ahd triggering the shutdown. Replacing the paste can’t hurt any worse than currently. (And replace the PRAM battery while I am at it.)
3. If that works, source a new graphics card for the 2011 imac, and try baking the 4850 GPU to extend its life in the meantime.
4. And possibly the easiest: Get an HDMI-in, mini Displayport-out cable, so I can use the 2009 iMac as a 27-inch monitor for my work laptop!

 

[Nguyen Duc Hieu]

[*]And possibly the easiest: Get an HDMI-in, mini Displayport-out cable, so I can use the 2009 iMac as a 27-inch monitor for my work laptop!

For this item, be reminded that cables are directional. Sourcing for the correct cable may become your nightmare. The below link is an example, but stocks are depleted.

QGeeM 4K x 2K HDMI Male to Mini DisplayPort Adapter

HDMI TO Mini DisplayPort adapter/ HDMI to Mini DP/ Ultra HD/ HDMI to Mini Display port converter/ HDMI to Mini DP adapter specifications : - HDTV resolution supported: up to 1080p@120hz, 4Kx2K@30Hz - Audio: 7. 1 Channel surround audio up to 192 kHz sample rated - compliant with VESA Dual-Mode Dis...

www.amazon.com

HDMI-compatible to DisplayPort Converter Adapter Male to Female Extensions 4K Cable 3840x2160 with USB 2.0 Power for laptop PC - AliExpress 44

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

 

[Quondam2009]

For this item, be reminded that cables are directional. Sourcing for the correct cable may become your nightmare. The below link is an example, but stocks are depleted.

QGeeM 4K x 2K HDMI Male to Mini DisplayPort Adapter

HDMI TO Mini DisplayPort adapter/ HDMI to Mini DP/ Ultra HD/ HDMI to Mini Display port converter/ HDMI to Mini DP adapter specifications : - HDTV resolution supported: up to 1080p@120hz, 4Kx2K@30Hz - Audio: 7. 1 Channel surround audio up to 192 kHz sample rated - compliant with VESA Dual-Mode Dis...

www.amazon.com

HDMI-compatible to DisplayPort Converter Adapter Male to Female Extensions 4K Cable 3840x2160 with USB 2.0 Power for laptop PC - AliExpress 44

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

Yes, it was a nightmare just trying to find the right directional cable. Searches kept turning up Displayport-to-HDMI cables instead of HDMI-to-Displayport.

I found the following, which at least had male connectors at each end, at the cost of using a USB port on the laptop:

https://www.amazon.com/DisplayPort-...patible-Monitor/dp/B093DQQ63M?ref_=ast_sto_dp

The price is good, but no reviews make me wary.

 

[Quondam2009]

I was playing around with some old archived software and found that...

DarwiinRemote works on an late-2009 iMac running High Sierra!?! I've dug up my old Wii remote and I'm setting it up for old-school gaming, baby!

 

[Quondam2009]

After using this computer for most of the week w/out a problem, I ran into my first issue last night.

The computer appeared to go to sleep just as I was walking back up to it. It wouldn't wake back up, however. On reboot, it would go halfway through the boot-up process, then shut down or reboot again. This happened even when trying to boot to safe mode.

I tried several attempts to restart the computer, and resetting the PRAM and SMC -- nothing was allowing me to get to the desktop without another shutdown or reboot.

I decided to see if it was the RAM causing an issue. I pulled out all the RAM, then put back only the late-2009's RAM. Only then, the computer started without any issues. (Hmm!)

To test that it was the RAM causing it, I put back in the mid-2011's RAM and restarted. It booted to the desktop again, with no issues?!?

I've run the full AHT and I've run memtest for 12 loops (using the Rember app), and neither reported RAM errors. The temperature of the CPUs were only a max of about 60° C the entire day, according to Macs Fan Control. I checked the logs: No errors were listed with the last shutdown cause.

Right now, I'm kind of mystified as to what the cause was. Overheating? Failing RAM? Failing PRAM battery? A dreaded GPU failure? I carried only the ODD, the RAM and the GPU from the 2011 iMac to the 2009 iMac.

ideas?

 

[Nguyen Duc Hieu]

I decided to see if it was the RAM causing an issue. I pulled out all the RAM, then put back only the late-2009's RAM. Only then, the computer started without any issues. (Hmm!)

To test that it was the RAM causing it, I put back in the mid-2011's RAM and restarted. It booted to the desktop again, with no issues?!?

I've run the full AHT and I've run memtest for 12 loops (using the Rember app), and neither reported RAM errors. The temperature of the CPUs were only a max of about 60° C the entire day, according to Macs Fan Control. I checked the logs: No errors were listed with the last shutdown cause.

Right now, I'm kind of mystified as to what the cause was. Overheating? Failing RAM? Failing PRAM battery? A dreaded GPU failure? I carried only the ODD, the RAM and the GPU from the 2011 iMac to the 2009 iMac.

ideas?

Similar symptom as my Windows PC.
After remove the RAM (2 of 4 sticks), the machine runs fine for months.

 

[California]

OP: Was ram your issue? Let us know. Clean the pins on the ram chips themselves btw.