Welcome to the forum
My bad, I linked to wrong post. Here's the relevant one:
If you're looking for advice, the best way to get it is by providing as much information as possible right from the start. This allows other readers the context they need to point you in the right direction. Here are some suggestions to improve your chances of getting solid answers: What should...
Of particular interest are:
Exact make & model of your Power Supply;
Motherboard—thanks for that;
Case & cooling parts;
Graphics card—thanks for that;
Monitor model & Hz;
Resolution you're running at;
What graphic settings level have you enabled?
I'm no hardware expert, but I assume you have an old PC—so sadly some part may have failed.
Are all drivers & BIOS up to date?
Have you tried the simple step of uninstalling and reinstalling the game?