iMac 21.5" 2010 - GPU Replacement - Not booting

[2wenty2wo]

Hi Everyone,

First post here. I read the iMac 2011 GPU Upgrade thread and I decided not to reply to that thread as my situation is not a normal case. I'm not sure if anyone can help me here, but after reading that thread I know there are some very educated people on this forum.

Backstory:
I was given a free iMac 21.5" (Mid-2010) from a friend, he picked it up from someone throwing it out and I have zero knowledge of this iMacs history before I received it. Most people would just scrap this for parts but since I'm currently typing this post on a MacBook Pro 15" (Mid-2009) in 2020, I thought what could I do with this thing.

What I've Done:

1. Turned it on, it had no start up chime, it beeped very loudly and the screen remained black.
2. I checked the RAM slot and it was empty. I installed some RAM I had removed from an old Mac mini.
3. Turned it on, I get start up chime, no beep anymore but the screen remained black.
4. I opened the iMac up and removed the LCD, I noticed a screw was missing, this has been opened before.
5. First thing I noticed was the LCD wasn't connected at all. I also noticed the backlight connector and the v-sync connector were damaged (but pins were still good and is fixable).
   
6. After removing the LCD, the second thing I noticed was the hard drive was missing (including the bracket), so I now assume the iMac stopped working, they opened it up, removed the hard drive, kept the RAM and tossed everything else.
7. I mounted a spare SSD using metal brackets I had, this works.
   
8. I also noticed a metal clip was loose in the iMac, and I found it was meant to be mounted to the CPU heatsink, now I'm thinking the logic board has been removed or at least attempted to be removed).
9. With the iMac started up with or without the LCD screen attached, the logic boards diagnostic LED's only show LED #1 & #2. LED #3 & #4 remain off. Looking into this, I found the iMac 2011 GPU Upgrade thread and thought, well, seems all signs are pointing to the AMD GPU dying - being an old iMac in the 2009-2012 era, they just took the RAM and hard drive and were done with it.
   
10. First I removed the "dead" AMD GPU and baked it in the oven for 10 minutes at 200°C. Plugged it back in, no 3rd LED.
11. Ordered a NVIDIA Quadro K1100M GPU to replace the AMD card. Following the GPU Upgrade thread, it looked as simple as booting from the USB, SSH in, update VRAM on the GPU and we are back to a working iMac.
    
    
12. I installed the K1100M into the iMac, noticing that the 3rd LED is still not lit (I read a post in the GPU Upgrade thread that said you won't get that LED until the card has been flashed so I wasn't too stressed at that point).
13. Made my bootable USB (tested it on my MacBook Pro - boots), plugged it in to the iMac, turned it on, I get the start up chime, fans run quietly, I look for the iMac on my network using a IP scanner - can't find it. After a little while the CPU fan runs at full speed and doesn't slow down at all. I still can't find the iMac on the network...
14. I notice there are no activity lights for the port going to my iMac on my network switch... No wonder I can't find it, it's not communicating.
15. I removed the GPU, cleaned the contacts with contact cleaner, reinstalled. Same issue.
16. I know the USB ports on the back of the iMac work because I was able to clear PRAM with a keyboard, so I connected a ethernet to USB dongle, this shows there is network activity at the network switch but I can't find the iMac on the network. I guess the dongle will communicate with the switch regardless if the iMac is involved or not...

So now I'm kind of stumped. Do I have a bad logic board? Seems I have no network at all? I was hopeful of this working because I was getting the start up chime but it seems it's stalling somewhere but I just can't see - This is all very hard to troubleshoot when I have no display.

I know I'm going to get the "give up", "buy a new iMac" reply, but this was just a "why not" situation, let's see if we can get this thing working. I already bought the GPU so I'm kind of invested. ?

I can't help myself sometimes, I just really wanted to see this thing turn on, it's such a pretty looking computer. ?

Thanks for your time.
Shaun

 

[Roman78]

Is that the HP or the Dell Alienware version of the card?

Alienware should work right away, but HP not. You can try to flash the Firmware from Nick onto it. Therefore you need a CH341A.

 

[2wenty2wo]

The eBay listing said it is a HP card.

Yeah I thought about that, I need to buy the clamp and everything. I just thought I would be able to boot into the live Linux USB that’s posted in the GPU upgrade thread and SSH into it.

I removed the CPU and the pins look fine. I remounted it. I just think it’s weird that it gives me the start up chime but I get no activity at the Ethernet port. I also tested a Apple USB Ethernet dongle and I get no activity. I’d honestly think the logic board is dead but that fact that it completes its POST baffles me.

 

[Roman78]

Nope.. HP Card would give a screen output at all.

 

[2wenty2wo]

I don’t have any GPU installed currently, I’m just trying to see if this iMacs ok. I understand I need to flash the GPU card to get it to display on the LCD but my concern is I’m not sure the iMac is actually booting despite it doing the start up chime.

 

[Roman78]

It should work without a GPU installed. You need to activate the Remotedesktop on the installation, after that you should be able to make a VNC connection to the machine.

 

[2wenty2wo]

That was my understanding too. I don’t have a hard drive or SSD connected either. I’m just trying to boot from the USB that is linked to on the upgrade thread.

I just don’t know what it’s doing when it’s “booting”.

 

[Roman78]

Hmmmm hard to tell, i did not tried the USB-stick yet.

 

[2wenty2wo]

I’ve used the stick on my MacBook Pro and it boots so I know it’s good.

 

[Lyca]

I’ve used the stick on my MacBook Pro and it boots so I know it’s good.

Did you resolve this problem? I have a 2010 iMac 27 doing the exact same thing - USB flash (xanderon) works but don't see machine on LAN. However, I did see the LAN address appear a couple of times but not with the GRML name... Also couldn't SSH into it (got timeout).

 

[Nguyen Duc Hieu]

Did you resolve this problem? I have a 2010 iMac 27 doing the exact same thing - USB flash (xanderon) works but don't see machine on LAN. However, I did see the LAN address appear a couple of times but not with the GRML name... Also couldn't SSH into it (got timeout).

There would be no GRML name displayed.
I open the network monitoring page on my router, and pick the IP address of the only device that have no name.
A screenshot of the router monitoring page before and after the iMac booting will help a lot. The new device appears on the list is the iMac.

I was lucky to SSH successfully right on the first time.
Try pinging to that IP address several time.
Check your SSH command syntax.
Check the SSH password. There is a password.

 

[Lyca]

Thank you for the input - I tried repeating and checked syntax but still have the problem (I may have a bad logic board). I'm hoping to hear from 2ewnty2wo to se how he resolved this on his 2010 21.5 iMac.

 

[The_Croupier]

Thank you for the input - I tried repeating and checked syntax but still have the problem (I may have a bad logic board). I'm hoping to hear from 2ewnty2wo to se how he resolved this on his 2010 21.5 iMac.

Is the original GPU completely dead? If no reinstall it and check if your ethernet port is working.

No point trying to SSH if you can't verify your mac is present on your network.

You haven't given much info, I really hate having to prompt for information but here goes, did you try all LAN ports on your router?

It would be rare for the port to just die by itself but I have killed a ethernet port on a 27" by accidentally bridging the logic board to the PSU while live, I got around the issue by using a thunderbolt to ethernet adaptor but this wont work on your 2010 as it only has display port.

You could however try a USB to ethernet adaptor.

There would be no GRML name displayed.
I open the network monitoring page on my router, and pick the IP address of the only device that have no name.

Not necessarily, it will depend on your router, as you can see mine display the IP and name GRML.

 

[The_Croupier]

Double post Soz.

 

[Lyca]

Thanks for the input. I have a few routers - connected my Macbook Air and iMac 27 to an Airport Extreme with no luck, connected both to a TP-Link AX3000, as well as combination thereof with no luck. Also connected the iMac directly to my Netgear FVS318 with no luck. In all cases, I see the iMac IP addr. but only get timeouts. Depending on port configuration and which router is in the picture, I get a name (*, Local-xxx, etc.) but not GRML. Additionally, after a while, the iMac IP address disappears. I'm stumped.

Also, I have successfully connected via secure shell from my Macbook Air to iMac with remote desktop activated. however, remote desktop should be irrelevant (??) since OS-x is not in the picture. right?

iMac bootrom ver. = 99.0.0.0 ; SMC ver. = 1.59f2

 

[Lyca]

I have also used several USB sticks with flash on them to no avail. All of them work on iMac when original video card is installed and I boot up with boot option.

 

[The_Croupier]

And with original card installed ethernet is working in OSX High Sierra?

 

[Lyca]

Yes, OS-X High Sirerra, original GPU - all is working.

mid 2010 iMac 27
2.93ghz i7
16gb ram
Bluetooth 4.0
1TB SSD

 

[The_Croupier]

Ok how about with original card installed and boot to GRML so you can see the command line and at root@grml ~ # type ifconfig
It should list your Mac's IP

If your Mac's IP is listed get a SSH app for your phone and see if you can connect: root@yourmacip

 

[Lyca]

Thanks. Didn't want to do this since I could SSH with the old card in BUT... my Macbook Air couldn't see / attach to anything on the host USB chain. I then used to a W-10 PC and immediately got a response on the USB drive connected to the iMac. I tore down and rebuilt again with the new video card and, using the PC' SSH, was able to flash! I don't know why the Macbook Air didn't work - that's a problem for another day.

I guess, at 70, my analytical and basic troubleshooting skills are waning. Thank you again for your patience constructive help!