I have changed everything but my dual 8800gt's and I still recieve this issue. It either tells me that the nvldkkm.sys or whatever cuases a BSOD, or it doesn't tell me what when it locks up. When it flashes random colors I get no reason why and it's a complete lockup.
I have the latest drivers. Do you think this is an issue with the gfx card or just a driver issue? Running win7 64bit
Download Driver Sweeper
, uninstall video card drivers, boot to Safe Mode and use Driver Sweeper to clear left over drivers, boot again to normal mode and install the newest drivers.
If this does not work, check what the card temperatures are when under load.