iMac 2010 white screen, no obvious fix

[Twixt]

Hello Everyone,

I seek advice for my sick 2010 iMac which displays white screen since yesterday.
Before that screen was frozen and I switched off iMac with power button.
I tested the obvious fixes .
-cmd+R does not work, white screen still
-safe mode runs smoothy, nothing specific to say but restart leads to white screen after that
-wiped non volatile memory
-unplugged all peripheral devices didn't change anything
-hardware diagnosis leads to one error 4M0T/4/40000003 HDD-1514

I called apple assistance, they are surprised a fan motor could trigger white screen but can not do more as computer vintage is way too old for them to act

I would like to try to fix this by myself before possibly going to a affiliated apple repair service. I called 2 of them and they already told me a fixing quotation would not be free and knowing iMac's age it is very likely they will not be able to fix it...

 

[Nguyen Duc Hieu]

Replace the HDD may help.

 

[Nguyen Duc Hieu]

Hello Everyone,

I seek advice for my sick 2010 iMac which displays white screen since yesterday.
Before that screen was frozen and I switched off iMac with power button.
I tested the obvious fixes .
-cmd+R does not work, white screen still
-safe mode runs smoothy, nothing specific to say but restart leads to white screen after that
-wiped non volatile memory
-unplugged all peripheral devices didn't change anything
-hardware diagnosis leads to one error 4M0T/4/40000003 HDD-1514

I called apple assistance, they are surprised a fan motor could trigger white screen but can not do more as computer vintage is way too old for them to act

I would like to try to fix this by myself before possibly going to a affiliated apple repair service. I called 2 of them and they already told me a fixing quotation would not be free and knowing iMac's age it is very likely they will not be able to fix it...

It's clear and obvious to me: Your HDD is failing.

 

[Twixt]

Thank you for prompt reply but HDD is doing well, I tested it once in safe mode and no error to fix

 

[Ruggy]

It definitely sounds like the HDD isn't loading the OS.
You say you checked it in safe mode does that mean in safe mode it boots and doesn't display white screen?
Have you tried booting from the original installation disks? (the ones with pictures not the grey ones)
If you've used hardware diagnostics use the one on the installation disk and use advanced mode if you haven't as it finds more.
If you think it's the screen or graphics card then using an external display- a TV with HDMI and a cheap dongle will do
If you have an OS on an external drive then you can boot from that. It will be slow but it's just to test.
It really looks like the boot sequence is getting stuck. It could be a software error somehow but it's typical of a failing HDD. It can take a long time for them to boot sometimes when they are failing so make sure you give it time.
That's all sorry.

 

[jowaju]

It’s the video card failing, almost certainly. You don’t say whether it’s a 21.5” or 27” iMac, or what video card you have. Should be either an Ati 4xxx series or Amd 5xxx series. The 5xxx series fail A LOT, the 4xxx not as much but still possible. Boot into wage mode and see what you have.

 

[Ruggy]

Further thought: you could try resetting the SMC if you haven't already. That can be the cause of odd screen problems on start up.

 

[Twixt]

Further thought: you could try resetting the SMC if you haven't already. That can be the cause of odd screen problems on start up.

Thank you for suggesting, I forgot to list it but I also did it with no change unfortunately

 

[Twixt]

It definitely sounds like the HDD isn't loading the OS.
You say you checked it in safe mode does that mean in safe mode it boots and doesn't display white screen?
Have you tried booting from the original installation disks? (the ones with pictures not the grey ones)
If you've used hardware diagnostics use the one on the installation disk and use advanced mode if you haven't as it finds more.
If you think it's the screen or graphics card then using an external display- a TV with HDMI and a cheap dongle will do
If you have an OS on an external drive then you can boot from that. It will be slow but it's just to test.
It really looks like the boot sequence is getting stuck. It could be a software error somehow but it's typical of a failing HDD. It can take a long time for them to boot sometimes when they are failing so make sure you give it time.
That's all sorry.

Yes safe mode is the only scenario where I do not have white screen at the end; display in this case is perfectly fine
I can not use original installation disk, I swapped optical bay to install an SSD instead (which I removed to check if problem was coming from it)

 

[Twixt]

It’s the video card failing, almost certainly. You don’t say whether it’s a 21.5” or 27” iMac, or what video card you have. Should be either an Ati 4xxx series or Amd 5xxx series. The 5xxx series fail A LOT, the 4xxx not as much but still possible. Boot into wage mode and see what you have.

Sorry I forgot to mention it as it is in my signature, it is a 27" iMac with an ATI 4850 if I remember well.

Boot into wage mode and see what you have? < what do you mean exactly ?
I performes advanced hardware test and still get the same error code : 4M0T/4/40000003 HDD-1514

 

[Fishrrman]

"safe mode runs smoothy, nothing specific to say but restart leads to white screen after that"

I doubt this has anything to do with the internal hard drive.
The GPU has failed.

When you boot to safe mode, you are by-passing the GPU and booting/running with the CPU's integrated graphics. The failed GPU isn't used.

That's why it will boot into safe mode, but not a regular boot (which needs the GPU).

It might be "fixable", but I wouldn't spend more than $25 on it.

After 11 years, it's time to start considering a replacement.

Hmmm... there are threads in the MacBook Pro forums about using software to permanently disable a failed GPU (and run with integrated graphics only). Not sure if this fix can work on an iMac.

 

[Twixt]

"safe mode runs smoothy, nothing specific to say but restart leads to white screen after that"

I doubt this has anything to do with the internal hard drive.
The GPU has failed.

When you boot to safe mode, you are by-passing the GPU and booting/running with the CPU's integrated graphics. The failed GPU isn't used.

That's why it will boot into safe mode, but not a regular boot (which needs the GPU).

It might be "fixable", but I wouldn't spend more than $25 on it.

After 11 years, it's time to start considering a replacement.

Hmmm... there are threads in the MacBook Pro forums about using software to permanently disable a failed GPU (and run with integrated graphics only). Not sure if this fix can work on an iMac.

GPU it must be then :/ Is it possible to have a permanent bypass of GPU and use integrated graphics instead ? Not sure it is possible with late 2009 gear, I remember MBP from 2011 could do it though

"It might be "fixable", but I wouldn't spend more than $25 on it" : any hardware based solution you have in mind?

 

[Nguyen Duc Hieu]

GPU it must be then :/ Is it possible to have a permanent bypass of GPU and use integrated graphics instead ? Not sure it is possible with late 2009 gear, I remember MBP from 2011 could do it though

"It might be "fixable", but I wouldn't spend more than $25 on it" : any hardware based solution you have in mind?

Your iMac 2009 is using a core i7-860 or i7-870, which doesn't have iGPU.
If you are sure that the GPU is bad, spend about 50$ to replace it with a modded Dell M5950m card, or HP 6770m card (quite complicated process) and use it as a monitor. 50$ for a 27" 2k monitor. Quite a bargain, eh?

I bought a 27" 2009 iMac for 150$ (GPU dead), spent 25$ for a 2nd hand Quadro K1100m, and now my son is using it for online studying, thank to all the small gadgets (speakers, webcam, microphone) it's already equipped with.