sometimes the flickering pixels is artifacting if its been overclocked or somebody used it as a mining card and pushed it too hard then sold it. or it could be the cooler was unscrewed and not properly seated but 75 degrees sounds normal.
So other than that software issues that might be causing shimmery pixels are your resolution scaling is wrong or you're upscaling. But it can also be in some situations using supermultisampling antialiasing is better or FXAA instead of TAA.
you may have been using RSR/FSR/DLSS on too low a resolution. bit its maybe your bit depth is too low for your lighting/graphics or if you have multiple graphics cards or like an APU and a GPU when you set a custom setting like anisotropic filtering high, some settings though they can be enabled in a config file many times very often or in numeric values thousands of times the quality of the lousy intel/nvidia default game graphics quality at ultra levels on any title in the universe.. theres sadly a limit to some features in the largely crippled and faked and never turning on or using the hardwares ability unless you type it in manually yourself with a config text file AMD adrenaline display drivers. in that they start to have issues if more than one card is enabled at once. but often its a resolution/bit depth thing or a issue or a resolution/rescaling issue or you've set your lighting to too low or high quality or some of its light functions have been enabled twice or too many times.
so toggle all your settings and type in and delete what you want to use in registry and a config.ini text file and see if you can get it to pretend to work.. your reality simulation realtime gaming with ray tracying then better ray marching then better ray casting all at once with fulltracedlightpathways and truelight and a heap of cool stuff.. should be infinity resolution rendering a reality simulation with infinityxsupermultisampling and look FANTASTICLY amazing. and your youtube and netflix should become real life like walk out of your TV almost.. feel like put your hand to it. works with my AMD mobile phone LG V60 same settings and my radeon 5700xt and ryzen 5700G.
but umm one of the things that can cause the pixel shimmer is maybe you got a virus or something. try secure erase SSD and ensure core isolation and memory integrity on TPM 2.0 and secure boot all that stuff. if you've a heap of large games downloaded and dont want to redownload them with a total reinstall and secure erase in bios of all your drives consider copying them out of programfiles dir to c:\ or to an alternate location like i do for steam when installing so i can "reset" windows anytime and keep files and they stay.
the other thing it could be is your BIOS RAM may be wrong try disable XMP leave it to auto.
