I have a asus P5GC-MX , i install a nvidia 9500GT
Did you install the drivers ->First from the CD, then install the graphics card?
No? Start over.
Once you install a device, Windows rushes over to match a driver with it. If you do not have THE driver already installed, (So Windows can find it), Windows will match up one of it's thousands of Generic drivers, or use the Onboard graphics driver already in use.
Power down, unplug the computer from power. Remove the graphics card observing anti-static precautions.
Press the Power On button in, and hold it in.
Hold it in for a count of Five seconds. (Count, 1001,..1002,..1003,..1004,..1005)
Let go of the Power On button. Do this procedure Two more times.
What you are doing is resetting BIOS back to the factory default settings, and clearing CMOS Error Codes.
Now plug your monitor back into the VGA port, in the I/O area of the Asus P5GC-MX mobo.
Plug the computer back into power. WAIT 1 minute, turn the computer on. When Windows has fully loaded, and all of your Start Menu programs, install the Drivers CD for the Nvidia 9500GT in your optical drive. Install the software.
If it asks you to restart your computer, Do Not at this time. Shut the computer down normally. Unplug from power. Observe anti-static precautions. Plug the Nvidia card in. Plug the monitor into the Nvidia card. Close the computer case.
Plug the computer back into power. WAIT 1 minute, turn the computer on.
Now, hows that?
[Advanced PCI/PnP Settings should be:
1.Plug n Play O/S -> No
2.PCI Latency Timer -> 64
3.Allocate IRQ to PCI VGA -> Yes
4.Pallete Snooping -> Disabled
5.All IRQ's (3 through 15) are set to -> PCI Device]