Been working on a Compaq Presario today. The VGA port has been waggled so hard that it can only run a monitor if the cable is held at a certain angle. The motherboard has a PCI-E16x slot so I bought an Nvidia PCX5750 card off eBay, thinking I could bypass the internal graphics. But the PC simply refuses to see it. So, discounting it being a duff graphics card, why won't it see it? I've set the BIOS to use PCI-E16X for default graphics, and installed the latest Nvidia drivers.

You say you've set it to use the PCIe by dafault. I'd assume that that overrides the onboard graphics. Is there a seperate option to competely disable the onboard graphics?

That card is from 2003.

I'd be surprised if there were drivers for it in the latest Nvidia pack.

I'd try another card. Let me know if you want me to send one to you, I've got a few working 6200's sitting around I've pulled from machines