Computer beeps 3 times and doesn't start up?

Hey TSG. Yesterday, I helped my friend upgrade his computer. He bought a new case, power supply, and a new GPU. When we started the computer up it beeped 3 times. It's not the RAM or the BIOS as I tried installing the old GPU and it booted up fine. I'm guessing it's either an incompatibly between the GPU (Asus GTX 760) and the motherboard (Joshua uATX) or a faulty GPU. Is there any way I can test what the problem is?

Thanks in advance.