GPU Not Functioning In 8x or 16x PCI-E Slot

[pikapals647]

This is my motherboard: https://www.newegg.com/Product/Product.aspx?Item=N82E16813128991 I recently swapped cases. My GPU has never worked in the 8x or 16x slot, only in the 4x. In my old case, I could just barely fit it in the 4x slot, but my new case will not allow for it(4x slot is on the edge of the board). I must have my GPU in either the 8x or 16x slot. When booting I get no picture and I'm sure I don't get as far as Windows either, I also get a red light on my motherboard and under it reads "VGA_BOOT". According to my manual it is a video card related issue. I have also tried booting without battery, any ideas?

 

[cin19]

What is your GPU? also what PSU did you have?