I replaced my card once, installed a fresh version of windows and updated all drivers before changing my psu. If you haven't done those, please do those first as they are free and relatively hasslefree than changing your entire psu.
The reason for this happening is basically your powersupply either overvolts your gpu and your gpu's safety mechanism gets triggered, hence it switches itself off or it is that your psu is very weak for your gpu and everytime your gpu gets a powerspike, the current protection in your powersupply gets triggered and hence this happens.
I tried searching forums for a solution, but I didn't actually stumble upon one which provided any guarantee, but yeah some did hint on the possibility of a faulty power supply.
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