new gpu low fps

I recently suffered a GPU hardware failure and had to replace my old 2080ti. I opted to replace it with a 4080 super, but I've been having significant issues with it since then. In addition to quite bad and frequent FPS drops and lag spikes, I cannot fullscreen games or discord streams anymore...

So i just upgraded my old gpu with new one 750ti to strix 970 and am getting 30 to 20 fps in csgo using the new gpu .But when i use 750 ti i get 60 to 80fps but now i get like 20 in every game i even upgraded my power supply to EVGA 500 w . pls help i just dont know what i need to do to get...

Brand new 1080ti, bought 2 tried both and getting lower fps than my 1070ti, i have a i5 7600k 850w ps, i tried ddu, still not working redownloaded all drivers from nvidia, even updated windows 10 and put power to high performance, i tried so much, can someone help me please, yes the vga is...