I would like to install a gigabit network adapter into a dell vostro which already has a built in one on the motherboard. When I install the PCI card the computer won't turn on. I run XP. How do I disable the built in adapter?
Whilst it's common for two similar devices on the same system to cause a resource conflict which in turn would prevent Windows starting normally, it should not prevent the PC from powering up, so that might have some other cause altogether.
The integrated network adapter (often referred to as "On-board LAN" in the BIOS), can be disabled in BIOS Setup, but you can't get into BIOS Setup if the PC won't turn on.
I suspect something else is amiss, so remove the new network card, then see if the PC will turn on. My guess is it won't, in which case you have another kind of hardware problem that needs fixing.