GPU Not Detected

[Jroy000]

This isn't my PC I'm working on it for a friend. I was just simply installing a new Mobo, GPU, GPU, and Ram. So I hook everything up and voila! it boots but then I get two beeps. I looked on Intel's website and apparently that means it cannot detect the GPU. I tried with another GPU and even a different pci-e port. But to no avail. The motherboard is an ASUS P5Q Pro
And the GPU is a gigabyte GeForce GT 720. The other GPU I tried to see if it worked was a Gt 210. Also these parts were used in another system and worked fine. So there likely isn't any compatibility issues. Also the CPU doesn't have onboard graphics nor does the Mobo support them. Thanks for your help!

 

[Jroy000]

Also I forgot to mention it is getting power. The fan is turning on. It just doesn't display anything.

 

[smorizio]

new mb 75w come from a 4/8 pin power plug. make sure your using the right pci-e power plug. the gpu ones are the 6 plus 2 cables. on some power supply they use two 4 pin cables with a clip to make 8 pins.

 

[Jroy000]

new mb 75w come from a 4/8 pin power plug. make sure your using the right pci-e power plug. the gpu ones are the 6 plus 2 cables. on some power supply they use two 4 pin cables with a clip to make 8 pins.

I have the 4 pin plugged in. If I had the 6 pin it would short and not even turn on. The pc starts up. But it gives two beeps meaning "no GPU"