I was stable @ GPU +120 and mem +1000 on my 3080 - Clock frequency2,100 MHz (1,440 MHz)
 
 

Stock never changed it. But I have a fairly strong system behind it.
My 3080Ti at the same settings scores higher and yet only hits 2,040 MHz but seems I can push it higher just havent played around again.
 
For the most part today's systems and cards really do not need to be over clocked. Just keep them as cool as you can and let the auto boost do its thing..
Like my latest build 12700K being seen by the 3080Ti boosts the gpu above 2k on its own running around 60c during game play. Thats not bad in my book, I would rather have the card for years then beat it up trying to push a little more fps out of her. Just my 2 cents.
 
Over clocking is a sport and most do it for fun. I play a little to see where she can run then back her down for daily driving.........

kraade
Every program is going to have a different load and what is stable in one , wont be stable in another
I find running Kombustor for 25 minutes is pretty good proof of stability. watch for your temps and see if they stabilize , if they are still climbing , your only going to throttle the card nullifying your OC and just heating your house .
undervolting is finding a stable place your card will run at stock or close to stock speed and use much less power and you make much less heat 

Yeah I personally like to tune the fan curve so that boost stays as constant as possible with no throttling.

I got my 3XS system from Scan and have left everything at the speed's they'd clocked it.