Gpu isn't being recognized

Mullin34

Commendable
Oct 10, 2016
1
0
1,510
So I built my new computer and installed all the drivers no problem. But once I swapped out my CPU my gpu isn't working. Sometimes when I hotswap it, the fans run super fast which doesn't seem right cause it's not overheated. Or sometimes the screen goes black and the gpu won't even get recognized. I'm not sure what's wrong.
My parts:
CPU -- Intel Core i7 6700K
GPU -- GeForce GTX 960 (used)
M.B.-- MSI Gaming Intel Skylake B150 LGA 1151 DDR4 USB 3.1 Micro ATX Motherboard (B150M Mortar)

Ram-- G.SKILL NT Series 8GB 288-Pin DDR4 SDRAM DDR4 2400 (PC4 19200) Intel Z170 Platform

Power -- Seasonic M12II 620 BRONZE ; SS-620GM2 80Plus Power Supply

I went on canyourunit.com, and it's recognizing everything but the gpu. Keep in mind it was working before I swapped the CPU which I made sure I installed properly.

On my bios screen it reads
CPU temp 33 Celsius
Mother board 27
CPU speed 4.00 GHz
DDRspeed 2133