Is the power supply to blame?

Question

Video cards

Hello everybody.
I warn you right away: I do not consider myself a professional and do not try to mimic him; the content of my question may be able to infuriate you with the bright unprofessionalism on my part in the field of computer technology, so please correct me somewhere if necessary and point out errors that may seem too obvious to you for me not to notice them.
Essence:
My computer is built on a Chinese Kllisree X79P motherboard, a Xeon E5-2869 server processor, four sticks of RAM and a Gigabyte Radeon R9 280X video card. The case contains 5 fans, 2 hard drives and 1 SSD 2.5. All this feeds the PSU from Zalman at 500W. I suspect that since the change of hardware (motherboard, processor, RAM) my video card has started to work much worse, i.e. overheat, provide less FPS even in a not very demanding game (STALKER). I want to add that I took the video card from my hands; it works, but when opening the video card, when I changed the thermal paste, I noticed that some places were burnt on the board. Yes, I know that not giving it away for repair right away or throwing it away, and then using it, was the solution, peculiar only to a person with 47 chromosomes (please do not point me to this). But I want to know the exact answer to the question, because before the change of iron it worked much better, and I had no problems with overheating or performance.
Questions:
Is this due to the lack of power of the power supply?
Will buying a 600W or 700W power supply help, or should I still change the video card as soon as possible?