Apple iMac GPU failure and Apple Store Brighton: Motoring Computer Related forum

Computer Related > Apple iMac GPU failure and Apple Store Brighton	Computing Issues
Thread Author: car4play	Replies: 16

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New Thu 6 Mar 14 10:20

Apple iMac GPU failure and Apple Store Brighton - car4play

I wonder if any of you guys can help with advice?

My work machine is an iMac (27-inch, Mid 2011, Model: 3.4 Core i7). Back in January it started randomly freezing where the screen would suddenly go a colour (typically green) with vertical stripes down it.
Once it was in this state, you cannot even VNC in or SSH to it to reboot nicely. It's power off and then on. Sometimes it would go days between crashes but then lately it has crashed as many as 7 times a day.
The crashes can be so severe that even a reboot will not get the screen back.
I called an independent Mac repair shop ( www.thebookyard.com ) and they said they thought the GPU was overheating and becoming detatched. They had seen the issue before.
To confirm this I downloaded a GPU stress test application called GPU Test from www.geeks3d.com/softwares/.
My Mac runs the benchmark program called Furmark for about 15 seconds before crashing with the same kind of green stripey screen. It can't run the benchmark on there either without crashing.
We tested this program on our other iMacs (one an identical machine to mine but the i5 processor instead of an i7 and one an i3). They both can run any application on the GPU test suite.
The MacBook Air i7 I am currently using can also run anything from this GPU Test suite. All of these other Macs are less capable than mine.

I then checked and found this Mac has AppleCare which luckily expires this June. I looked up appointments on the Apple site and saw the earliest was with Apple at Lakeside. I called them and they said make sure it is TimeMachine backed up as they would likely simply replace the Mac. I didn't have time before the appointment to check the current TM backup was the complete one (because I had to use a smaller one to get my account onto this Macbook Air) so I cancelled the appointement and booked it in (in 4 days time) at my nearest store, in Brighton.
When they tested it with the Apple test suite they have there it came back with no faults. I assured them it is faulty, because why else would I bring it in. I showed them a picture of crashed screen after it had happened in normal use. (This one had vertical pink bars on a white background).
I then logged into the Mac with my account and ran the Furmark test and it crashed within 2 seconds leaving the stripey screen. The Mac also has a dark blotchy patch in the top right where the LCD has burnt in a bit. (The Bookyard guys thought this might be related to the GPU temperature as it is just next to this part).
Anyway, Apple told me that because it was not their program that had crashed the machine, they could not say there was a fault with it.
However, they did take it in and have it the best part of 8 days in which time they replaced the glass on the screen (there was apparently a chip on this on the LHS) and the LCD display and the GPU card.
I picked it up and back in the office re-ran the Furmark program to check it out. Silly me should have checked it in the store because it crashed within 2 seconds. Even faster than before it went in for repair.
I thought maybe it is just the application. Unlikely, but to check I downloaded another GPU intensive application called 'Heaven' ( unigine.com/products/heaven/ ).
My Mac would run this for about 20 seconds and during this time the displayed GPU temperature climbed steadily to 90 degrees at which point the Mac would crash with a completely black screen.
It was a job getting it to restart with a login screen after that.
All the other Macs in our office can run 'Heaven' until one gets bored watching it. On the i5 machine most like mine the temperature stabilises at about 60 degrees.
I rang the store and asked to take it back straight away, but was told I would have to book it into their system in the usual way. This would mean a delay of around 4 days before they would even see it. I called the support line instead and after they had spoken with the store they agreed to have it back at my convenience. I dropped it straight back that day.
The Apple technical line told me to stress to them that they need to run these programs to see the fault. I did.
They have had it another week or so and tell me that they have now changed the power supply and then now the main logic board. But when they run the 'Heaven' app the temperature still soars to 90 degrees and it cuts out.

So to recap, they have now changed the glass, LCD, GPU card, power supply and main logic board and it appears the problem isn't fixed. Maybe Apple Store at Lakeside was right that it would have been easier to simply replace the machine.
Now the problem I have is that Apple in Brighton are saying that because these applications aren't part of their test suite, they cannot say that there is anything wrong with the machine. The Apple test suite returns no fault after all.
And even if I were to get an official Apple program to crash it like Final Cut that would not still be proof that there is anything wrong with it. They tell me that these machines are NOT designed to run programs which are so GPU or CPU intensive. Because they are not part of Apple's own test suite they are no measure of a machine which has a fault. One should expect a mahine to fail if one runs it with such a stressful program.

I am almost speechless with them. I have run macs in my past engineering days for 5 days at 100% CPU. Our internet servers sometimes run for minutes at very hight loads. I cannot believe someone is telling me that if I run any task on my computer that involves high stress levels I should expect it to fail when this has not been the case for me in the past or with any of our other computers.
What I cannot get is the logic of it all. I see it like this:
1) my mac freezes randomly in normal use
2) Furmark can reliably reproduce this behaviour on demand
3) The Apple Hardware test suite does not detect any faults. (Clearly there is a fault so this suite IMHO is useless in this situation and we should forget it)
4) Despite changing pretty much the whole mac innards the Mac is failing under the same predictable 3rd party tests. So IMHO will still likely crash on a random basis in normal use.
5) Taking it back in this state (which is what they want me to do) and waiting for a 'normal' failure at which point I have to drive it back to Brighton and waith another 14 days for it to be turned around is simply not an option for me.
It's hard enough going on without my main work computer anyway.

Why didn't they simply take the pragmatic and less costly option of simply swapping the machine?

Last edited by: VxFan on Thu 6 Mar 14 at 10:33