Question Pc wont post when gpu installed?

[squantheman]

I recently got an HP pavilion with a pentium g630 and 6gb of ddr3 1333mhz. Without the GPU (Asus gt 1030) in, iposts and boots and works fine, but when I install the graphics care it won't post and gives me one long beep followed by 3 short, meaning ram problem. I've tried reseating and swapping the ram about but it fixes nothing. Trying to fix this up as a present for a friend but I have no clue what the problem is. Any help? tl;dr: PC works without GPU but doesn't with GPU.

 

[squantheman]

Tried removing ram and reinstalling in different slots. Ram isn't a problem, tested it in another machine. Also used a HDD with the drivers and all installed and it made no difference.