I have a BioStar TA790GX 128m 5.x motherboard with a Phenom X4 9850 CPU, 4GB of RAM and a 550W PSU.
The system crashes routinely whenever I install a GPU. It'll crash quickly when playing games but it'll also crash if I just boot the machine and leave it at the CTRL-ALT-DEL login screen.
I have tried installing both an ATI 5500 and an nVidia 9600. I have tried multiple versions of the Catalyst drivers and the latest nVidia drivers. The crashes occur on WinXP SP3 x86 as well as Win7 Enterprise x64. I don't think this is a software or driver issue. The crashes seem to occur more frequently with the ATI card than the nVidia but that's just speculation as I haven't really paid that much attention to the timing.
I have tried with and without the onboard video enabled but otherwise the BIOS settings are at the default settings.
Does anybody have suggestions as to what I could look at or change to fix this issue? Am I stuck with the integrated video?
With no peripheral GPU installed this machine has been rock solid and never given me any problems.
The problem is likely the PCIe slot. Sometimes they are damaged in shipping or just go bad. If this is the first time you're tried to use it, there would be no reason for you to notice that is wasn't working before.