LOW FPS after reboot PC, HELP PLEASE!

[Arthm0st]

When I turn on my PC in the morning, I don't have any problem with perfomance, all games run perfectly, but when I reboot PC, after loading, I get freaking stuttering in every game. For example: Euro Truck Simulator 2, cold start PC - 90+ FPS, ultra settings, after reboot or rapidly turning off/on PC, it has about 60 fps on low settings, and when I rotate my mouse, it drops to 30 fps, meh. And same thing happens with other games. But if I turn off PC and turn on it again after 30-50 minutes, it runs very smooth. Help me, guys, please. Is it a PSU problem or GPU?
My specs:
i5 3470;
ECS Z77H2-A3;
8GB Crucial;
GTX 1060 MSI 6GB (Bought on October 20);
PSU FSP 600PNR-I 600W.

Thank you guys.
From Russia with love.

 

[Arthm0st]

This is I'm talking about. 1 Graph, Cold start - pretty nice FPS in dirt rally and. 2 Graph, After reboot - drops to 40 fps, freezes only.

 

[Arthm0st]

Hello?

 

[Arthm0st]

Okay, thanks everyone, it was a mobo's trouble, I'll buy another.