My sons pc specs:
Gigabyte GA-Z68X-UD4-B3 Motherboard
I7-3770K CPU
R9 290X Vapor X 8gb Gpu
16gb gskill ram
128gb ssd
darkrock pro 3 cpu cooler
ocz zx1000 (overkill I know)
The issue:
I removed his R9 290x and installed my GTX 980 and booted the computer. The pc will power on, lights, fans but...