Question gpu falls on low usage ( 0-25%) and game starts freezing

[MoronicBat]

after like hour or two the game starts heavily lagging and freezing, i opened msi afterburner and looked up the gpu and when the freezes happen it's usage falls really low and then goes back and so. the temperatures are great btw.

i7-2600k 3.4ghz
gtx 750 ti no oc
8gb ram ddr3

1. installed updated bios
2. updated nvidia drivers
3. switched to older driver version

 

[rgd1101]

full system spec? include make and model of the psu

cpu/gpu temp and usage during the freeze?
ram/ssd/hdd usage during the freeze?