[SOLVED] PC Freezing problem: PSU or GPU? Or Both!?

[PugkinSoup]

Hi
So I've now spent a long while suffering with PC Problems
My PC Was fine for a while, until high voltage lines near my house exploded during a freak storm, my PC was on at that moment, then power was lost to my house.
since then my PC has had issues
Under (somewhat) intense loads, as in, only while gaming, I've had issues with freezing and some graphical glitches.
Sometimes I'd Have display connection issues, although i have personally confirmed this is due to the GPU HDMI port being a tad dodgy, only if this is interfered with is this an issue.
However, I can be playing a game for hours and have it suddenly freeze, the entire computer will lock up, with my only option to be to hold the power button until it switches off. Sometimes when these freezes have occurred I'll have graphical glitches.

Thinking it was a Gpu issue I sent My Gpu to RMA, it later returned with the only given information being it was "repaired".
Unfortunately since then I have had these issues reoccur, but I have also discovered something odd about my PSU
My PSU was preowned (Yes I know, its complicated) and makes significant noise, from whining to buzzing, but the weirdest part is that its amplified every time i move my mouse.

I'm somewhat descending into madness over this PC, Please help, what part would be causing this?

Thanks

Additional Information
PSU: Silverstone SX-500G Gold on internal power cable extension (only 2 electrical parts that are preowned), GPU :Asus GT 1030 OC, Intel 10400f, 2x8 2666 Corsair vengeance LPX ram, Asrock Z590m-itx/ax, Logitech G502 Mouse
Whole system is more than sufficiently cooled in a semi-open space

 

[DRagor]

high voltage lines near my house exploded during a freak storm, my PC was on at that moment, then power was lost to my house.
since then my PC has had issues

You always swap PSU after such incident as the very first thing. Do not use it anymore!
Of course other parts could be damaged as well, as in your case GPU was. And maybe something else, you don't know that. But you have to start with swapping PSU, then if there are still problems you can try troubleshooting them.