we need to disctint… we have a huge topic about the popup what I assume you see: Warning: Your graphics device has encountered a problem
In each (except bsod) case you should see an error message within the windows event log. Can you please check ?
More intressting is “black screen”. You mean a BSOD ( pc reboots ? ) or did “only” msfs window “go black” ?
For me the temps of gpu and also the PSU looks fine ( I own 2080ti with a 750w too , and really years old - its very rare if not a myth that 10years old psu can not deliver the same power. What can happen is, that e.g. some capaitors goes defect or bad , and so the quality of the voltage goes bad… but really, we speak then about 3…4 pc generations ). Its the same myth that thermal paste needs to be renewed after 2 years.
Also be aware that other reasons can cause that, e.g. RAM XMP mode, CPU , etc…