We're going to need some more information. Please include/list your specs like so:
CPU:
Motherboard:
Ram:
SSD/HDD:
GPU:
GPU:
PSU:
OS:
Include the age of the PSU and what you're doing that causes the screen to black out. If the system blacks out when taxed then it can be either the PSU or the GPU. Take note of which driver version you're on for your GPU at the moment.