Thx for your reply,
by crashing to desktop i mean that the application stopped working (windows message). I monitored temps while gaming and they never exceeded 55°C for both CPU and GPU.
I tested Prime95 only for about 1 hour, temps went up to 66°C CPU and 75°C for GPU (but stable, for at least this one hour i tested)
Crashes in game occur randomly, sometimes even after 5 min with a maximum of about 2 hour crash free gaming