Drops of FPS in 3D applications, only a reboot helps

Good evening, all.

The problem is that in games after some time the FPS drops dramatically. It can happen anytime, 2 hours after the start of the game or during normal operation of the computer. In order to recover FPS, you must restart the computer, nothing else helps.

Tried:
- To monitor the temperature of processor and graphics card, they are constant values (a video Card 60c, CPU 50c).
- Check task Manager, nothing loads the processor or video card, the extra processes.
- Reinstall windows, update all drivers to newest.
- Restart in device Manager, the video driver.

The computer collected itself, the only doubt in what may be the reason for the PSU, I have it on 450w, do it for the following iron?

My iron:
AMD Ryzen 1500x
MSI GeForce GAMING 4G GTX1050Ti X
Motherboard MSI A320M Pro-VD/S
Power supply 450W GIGABYTE

What could be the problem?