Nividia 8800 gs issues
Hi there,
I know it has been a few months since this post has been active, but it caught my eye while Google searching for something else and I wanted to post as I've had this problem a couple of times over the past few months.
I have an iMac 8,1 (early 2008), 24" with the Nvidia GeForce 8800 GS. It turns out there are a lot of complaints this year about the 8800, as apparently it wears out over a few years, and replacements (clearly refurbished, since they don't make the 8800 brand new anymore) fail quickly too.
I had my GPU replaced a few months ago, and it failed within a month. I paid about £200 having just been out of AppleCare cover period. When I took my iMac back again because of the same issues (freezing and graphical anomalies) the GPU and also the logic board were replaced, both free of charge this time (90 day warranty on original replaced GPU). No issues yet, but we'll see.
I think it's a known issue, but not QUITE big enough to have warranted a recall, so just keep getting replacements. If it happens again (third time) I'll see if they just replace the whole iMac and pay the difference for an upgrade.
INTERESTING NOTE: The tests at the Genius Bar both times showed a missing GPU Proximity sensor. Clearly burned out / melted off etc.