Z61m video problems (hardware)

[Zak]

I have a Z61m (9450-38U) that appears to be having video problems. The problem manifests itself differently depending on the software environment, but I'm reasonably sure this is a hardware problem, as it's displaying several groups of 1px vertical lines on the BIOS splash screen on initial startup, and physically twisting the base of the computer alters or eliminates the problem.

I don't think it's a screen/cable problem. When the OS (Linux) is running, there's a small rectangle of vertical grey lines surrounding the mouse pointer, and no other display glitches. Running a standard kernel, it will eventually panic (indicated by a flashing caps-lock indicator). Running a real-time kernel, applications stop responding to input, and the machine eventually freezes completely.

[Zak]

After some testing, it seems that my GPU has become highly sensitive to heat. If it gets over about 60C, the machine crashes or freezes. This was never the case before. Running the fan at full speed and using the basic ATI driver without 3-d acceleration is a workaround, but I'm wondering if anybody knows more about the problem.