iM 4,1-14,4 The iMac GPU vertical line temporary fix

[mortlocli]

This worked (for now) on my 2009 iMac (10,1) as a means to get data from the HD.

Background- a while back, I think I cooked the GPU while watching a movie using Linux and not realising there wasn't any fan control. The resulting vertical lines went away..but as can happen when probs go away by themselves..they can also return.

So here I was, wide vertical lines on start up. Apple icon and the horizontal scroll bar showing the boot up process (original internal HD), but about 3/4 way thru a sudden change to a pixelated screen..and all progress stops.

After several reboots getting the same result, I tried this:

On boot up, held down the Alt key so boot up options appear.
I didn't have my external SSD plugged in so the recovery, first and second HD partition appeared.
I found if I left things at this stage the pixelated screen didn't happen...even after a couple of hours.

Then if I selected the usual boot up drive ie first partition..id get the same as before ie Apple icon, scrolling bar then pixelated screen.

But here's the thing: on reboot - no vertical bars...for an hour or so. Enough time to copy files to an external SSD.
Yep..pixelation happened again..so repeated the Alt key start up and delay..again got a normal screen on reboot ..for all afternoon until shut down.

..so seemingly not a long term fix, but enough to recover data...so could be worth a shot.

 

[Juicy Box]

You can also use target disk mode, Hold “T” on start up and connect to another Mac using FW.

It basically turns your iMac into a giant, power hungry external drive. You can even boot another Mac that is compatible with the OS on the iMac, if you needed.

 

[mortlocli]

You can also use target disk mode, Hold “T” on start up and connect to another Mac using FW.

It basically turns your iMac into a giant, power hungry external drive. You can even boot another Mac that is compatible with the OS on the iMac, if you needed.

Ta - I lack a FW cable and they seem to be rare in NZ..though I've not really looked as have not (til now) had a need for one. Perhaps I better look for one.

Just booted up the iMac ..and no vertical lines..looks normal.
Not sure how long for though -ha.

 

[exploradorgt]

On boot up, held down the Alt key so boot up options appear.
I didn't have my external SSD plugged in so the recovery, first and second HD partition appeared.
I found if I left things at this stage the pixelated screen didn't happen...even after a couple of hours.

GPU problem, yes. I don't know all the answers or specifics, but I can tell you many of us with damaged GPUs were able of "using" the computers to some extent without screen glitches AT LEAST, when no advanced graphics were used, I mean: no graphics acceleration. That's why many suffering with GPU damage don't see any problem as long as they boot in repair mode. But anyway, your GPU is failing, and it will continue to fail and get worse. Even if you install Windows or Linux (like others did) and got some decent graphics... you won't really have sleep/wake functions, as this will freeze your computer.

You have to try baking your GPU or just replace it.

 

[mortlocli]

GPU problem, yes. I don't know all the answers or specifics, but I can tell you many of us with damaged GPUs were able of "using" the computers to some extent without screen glitches AT LEAST, when no advanced graphics were used, I mean: no graphics acceleration. That's why many suffering with GPU damage don't see any problem as long as they boot in repair mode. But anyway, your GPU is failing, and it will continue to fail and get worse. Even if you install Windows or Linux (like others did) and got some decent graphics... you won't really have sleep/wake functions, as this will freeze your computer.

You have to try baking your GPU or just replace it.

Ta exp, yes I have seen those baking suggestions and yep..expect its only a matter of time before my iMac fails completely. A more recent 'old' iMac aren't that expensive as a replacement...or (seeinng I have a spare monitor) maybe I'll go for a mini. The local council here runs a recycle program for failed or obsolete hardware. In hte meantime Im mainly using my 2006 17inch 5,1 iMac.

..so starting up with 'repair mode' doesn't have graphics acceleration? (Im not all that clued up with the workings.)

Yes.. I expect the GPU prob has variation with each iMac on which it occurs. Thought Id share my findings in case it proves useful to someone.

 

[exploradorgt]

..so starting up with 'repair mode' doesn't have graphics acceleration? (Im not all that clued up with the workings.)

So it seems, it's the explanation I've found while searching.

Many of us report being able of seeing video signal without issues, or with less issues during startup repair, or while just booting (progress bar), but things get ugly, stop, freeze, or go black after that.

 

[mortlocli]

So it seems, it's the explanation I've found while searching.

Many of us report being able of seeing video signal without issues, or with less issues during startup repair, or while just booting (progress bar), but things get ugly, stop, freeze, or go black after that.

Oh righty..so the acceration comes back on after the boot up?? And consequently the bar or pixelation prob returns?

 

[exploradorgt]

Oh righty..so the acceration comes back on after the boot up?? And consequently the bar or pixelation prob returns?

Yes.

I guess we can't say it's a bit of the same behavior like on Windows and Linux, the full drivers are only loaded right about showing the login screen, before all that the OS just shows some standard low res image and some animation.

 

[mortlocli]

Yes.

I guess we can't say it's a bit of the same behavior like on Windows and Linux, the full drivers are only loaded right about showing the login screen, before all that the OS just shows some standard low res image and some animation.

Ta for that..rather interesting difference bout how the Mac process is compared to Windows n Linux.