Question My PC reboots randomly

[Cbasx]

Hello to everybody, recently I changed my GPU, from a Nvidia Geforce GT1030 (5 yrs old) to a Radeon RX 590 (2 yrs old), it was from my brother, and he gave it to me because he didn't get any image (white screen), not from the GPU and not from the motherboard so he assumed it was a motherboard problem. I installed the new graphic and in mid game or sometimes idle it crash, the screen goes green or beige sometimes and the pc reboots. I tried a DDU in safe mode to clean all the previous drivers and installed the new ones from AMD and didn't work. My pc worked perfectly before the new graphic and its not a temperature issue (CPU and GPU don't go over 70C° . Any ideas of what could be happening?

My pc:
CPU AMD Ryzen 5 3600 6-core (5 years old)
SSD1 Toshiba OCZ TR200 240GB
M2 WD BLUE 500GB
MSI B450-A PRO MAX (5 yrs old)
Corsair Vengeance Pro DDR4 3200 CL16 2x16GB (New)
PSU 800W (5 yrs old)

Nvidia Geforce 1030 GT (old)
Radeon RX 590 (new)

 

[rgd1101]

brand and model of the 800w psu?

 

[steveb1976]

what make is the rx590? xfx, saphire, powercolor, msi, ?

 

[Cbasx]

It's solved, aparently the thermal paste was dry, I just opened the graphics card and changed it. Now is going perfect, thanks anyway.