T520 BIOS failure, possibly due to video card issues

[pkbooo]

I have a Thinkpad T520 with Debian Squeeze installed (although I'm not really certain how important my OS is; this seems to be a lower level problem?). The laptop came both with an integrated video card and a discrete video card, but until now I had only used the integrated Intel video card.

When "lspci | grep -i nvidia" returned nothing, I went on the forums and found it suggested that I change my BIOS settings to recognize the other card. I changed the video card settings to "discrete" rather than the former "integrated". Upon reboot the system immediately crashes. The screen does not reach the BIOS or even the initial Lenovo logo, in fact the screen fails to turn on entirely.

When the computer tries to boot, it loads all the lights (battery indicator, power button, etc.) but crashes immediately afterwards with a thunk THUNK thunk sound that sounds to me like the hard drive crashing. To my knowledge, there are no other indicators that could point to what's wrong and there are no beep codes.

This is my primary computer and I CAN'T not have it working. Please help (and thank you for your time!)!

Edit: If it comes down to it, any information about how to reset the CMOS on a Thinkpad T520 will be much appreciated! (oh, and it's a 64 bit Intel processor and the fingerprint reader works to *start* boot process)

Edit 2: Just removed the backup battery (have not reinserted it) and am receiving the exact same issue.

[Brad]

Try removing the hard drive and attempt to boot.

If successful I would then enter the BIOS and switch back to the original integrated GPU setting.

Then reinstall the hard drive.

Hopefully that fixes the issue temporarily.

Sounds like you may need to service your W520 if you need to use the discrete GPU.

Brad