PC usage low, but game performance bad

Daanhoek18

Commendable
Jul 27, 2016
5
0
1,510
when playing games, my usages are very low. cpu stays around 20% for example. the thing is, the performance of the games is also bad.

specs:
Motherboard: Gigabyte GA-P67A-D3-B3
GPU: AMD Firepro V5900
CPU: Intel Core i7-2600
8 GB of ram
Windows 10

i hope someone knows an answer to this, i've been searching for quite a while.

thanks in advance!