It really seems like replacing that with a higher rated name brand psu will resolve your problem. You’re running up against the maximum power the pcie slot is rated to deliver. Claimed wattage only tells part of the story. All that power for the card has to come through the 24 pin connector along with everything else.
If you wanna prove me wrong plug the motherboard/cpu/gpu into someone else’s higher rated power supply and show that it has the same behavior.
If there’s a computer shop near you they’ll probably do this test in front of you with one of their power supplies for a couple of bucks. If there’s a gamer friend they’ll do it for free to help you figure out the problem.
Don’t use a system you don’t understand.
There is no difference between deleting a file and encrypting it and losing the key.
Don’t start encrypting your shit if you don’t have a functional, operational, tested backup system in place.
Read the three sentences above again and make sure you understand them. Ask questions if you do not. It’s okay if you do not understand.