My GPU usage maxes out at about 20% ,but my CPU usage at about 80%, in CSGO.
CPU: AMD Phenom II x4 970
GPU: R9 270 2GB GDDR5
RAM: 4GB 1333 MHz
PSU: BeQuiet 400W 80+ Bronze efficiency
HDD: Western Digital 1TB 5400RPM
It can't be the HDD's fault, I was using it in a laptop before and worked fine.
My guess is that I don't have enough ram(?)