I wouldn't make this up.. Believe me, I wish it weren't true. I wouldn't have spent days troubleshooting, pleading with geniuses and trying to get someone to acknowledge that I am not abusing my $2500 computer.
Just google "nvidia solder packaging" and you will see pages of information to read. There are emails from NVidia personnel claiming the failed packaging "solder bumps & whatever sits under the GPU" was only used on laptop components, but tests were done on the compound and the high lead packaging was used on desktops too. HP, DELL , Apple and probably others were impacted since they had NVidia graphics cards installed. 8xxx & 9xxx series cards and who knows what else.
I'm not here to convince anyone, as my problem is now fixed. I'm just trying to help maybe ONE person who is desperate to get their PC running and has nowhere to go. People here need to realise that resetting PRAM and Diags are good starts, and if Applecare is available, it should be used, but the only remaining conclusion is not that the PC was mistreated and Apple scientifically engineered these machines to overcome any obstacle. They have flaws. I noticed right away with the backlight bleeding, screen darkening from heat, yellow tinting, HDD failure due to heat and now the GPU.
I just upgraded my iMac 8,1 to 6 GB RAM, that' how confident I am that mine is good for awhile, and if not, I can fix it again. My next step would be to upgrade my 1TB WD to a SSD to reduce heat even more, but those need to drop in price first.