You said this ( BTW, why not just updating the previous topic? ),
I'm usually terrible about giving advice, but this thread is still going without an answer.
I looked up your hardware and that card and motherboard seem to both be the old PCIE 1.0, so you should be ok. Have you disabled the onboard graphics in the BIOS? Just grabbing at straws now, but is this the first time that computer had a graphics card and maybe the power supply came free with a cheap case?
I appreciate your help. The only bad advice is the thoughtfulness not given. So, thank you!
I have definitely successfully disabled the onboard geforce graphics. I had the same concern you did. But, all drivers are removed, and it doesn't show in the hardware manager - not even as an unknown device.
I've took a look to the manual of your Motherboard here, http://www.asus.com/Motherboards/AMD_AM2/M2NMX_SE_Plus/#download
, and it seems that you cannot disable the onboard graphics adapter, but you can set the priority of the graphics device. You should go in the "Advanced" section and check the display device priority, you should have something like [PCIE -> PCI -> IGP].