I am trying to help my 16 year old build a PC. I purchased ''recommended'' parts and components. Everything went well except the video card does not seem to want to work. Maybe I got the wrong video card for the motherboard I got? I think I was suppose to get DDR2 instead of DDR3. My motherboard is: MB ASUS P5N-D NF750I SLI 775. My video card is: VGA EVGA 512-P3-N884-AR 9800GTX+. When I hook in the monitor and turn it and the PC on, I get nothing. Everything powers on, the monitor, keyboard light, tower lights and fans, but nothing on the monitor. I put the video card in the blue PCIEX1_1 slot, and connected to the power supply with a PCI-E cable. It has a supplemental power adapter, but I do not understand how to connect it. Please help! and Thanks!

Computers & Internet - Evga - e-GeForce 9800 GX2 DDR3 PCI-Express 2.0 -Lifetime Warranty, ...