Bad Display / Graphics Problem with iMac 24" 7300GT
hoping someone can help me with this.
So I assumed the problem was a faulty video card (7300GT) so I bought a new one and fitted it, correctly as I've done this a few times before.
However I'm still getting weird artefacts on the screen, thinking about it they ar different to the ones you get with the GPU overheating/sol
See the attached screenshots (a combination of red and blue repeating patterns across the screen that redraw whenever you alter the display, i.e. move a window)
So, although not totally ruling out the video card I'm at a loss as to what the problem is.
1.New GPU hasn't helped
2.Artefacts appear on startup (Not software then?)
3.Don't appear to be heat related (SMCfancontrol makes little/no difference)
4. Known working LCD does not alleviate problems
5.Logic board in good superficial condition, I can't see any obvious problems.
6. RAM known working
7. Safe mode makes no difference
So hopefully someone can figure this out?
What I'm leaning towards is
1. Bad new video card?
2. Bad VRAM?
3. Bad GPU daughtercard?
4. Bad Logic board to GPU interface?
5. Bad logic board?
6. Power Issues?
7. LCD cable problem?
Many thanks in advance!
Hook it up to an external monitor to help isolate the problem. If the artifacts are present on the external then the problem is hardware/video card related.
The 7300GT has a known issue with the capacitors on the card. The 7600GT was also an option for your iMac. They cost a bit more but you may consider it a cost effective repair vs the 7300gt loto.
I had the same artifacts problem on my iMac 24" with GeForce 7300GT onboard, Lion 10.7.5; it started like in the pic quite a week ago and got worse day by day, till the system used to hang just after rebooting.
Once I could succesfully login I removed the GeForce kext (all of them) and it became usable after rebooting... but I obviously lost all the "video" capabilities, from desktop effects to movie playing as graphic acceleration had been dropped.
I reinstalled SL but it could not get any far than the language selection window... it crashed every time I restarted! artifacts were also visible during installation!!
So I opened my iMac! cleaned up GPU and processor from the old thermal paste and applied a new one; removed the dust off the blowers, put it back together...
Tadah! It worked like a charm!
after restarting the system I could go through the installation steps, then I installed a fan/temperature manager app (there are plenty of them, just google it!) and pushed CPU blower speed up to 2000 rpm...
it looks stable, no artifacts, no crashes.
I think I'm staying with SL as the problem started with Lion, and with Lion I also had my MacBookPro GPU fried after a couple of months I installed it... just a coincidence?
Getting the same issue with an iMac using this GPU. It started right after upgrading the OS to Lion. Unplugging the computer for at least an hour "fixes" the system temporarily as it resets the SMC. Issue comes back and gets progressively worse over the course of a few days. For me, downgrading back to Snow Leopard was the "fix".