100% usage 100 C temp

[Julius_16]

My gpu overheat to 100 degrees celsius and then whole pc crashes to black sreen, but fans keep running up. Also my GPU usage is 100%

My build
GPU: Geforce GTX 580 Cod Bo
CPU AMD Phenom(tm) II X6 1055T
MOBO: M4A79T Deluxe
POWER: ? dont know

 

[RobCrezz]

You will likely need to remove the heatsink from the GPU and clean off the old thermal paste and apply new.