Did you buy yours from "Cecil"? He was binning 9900k xhips and installing the copper heat spreader back in 2/19. If so, it is probably a great chip. Mine has been runing at 5.1ghz @ ~1.33v for more than 2 years. GLWS.
I have a EVGA 2080ti FTW3 hydrocopper and am looking to possibly trade for a RTX 3090 plus cash on my side obviously...needs watercooled or block readily available.
If you have one and you are willing to sell it for a non absolutely absurd price, please let me know. Depressing looking at a new build running a 750ti and I have given up on a 30X0.
An AIO is definitely capable of cooling this chip. These are all using a push/pull Corsair H115i on an open bench at 5.1GHz 1.325v 0 AVX offset. The only thing it could not handle was Prime95 w/ AVX which is a pretty unrealistic load for most people. These were while I was testing my setup on...
9900k 5.1GHz 1.33v w/ no AVX offset. Memory 4200 17-17-17-37. Chip has been delidded with copper IHS installed and is under a Heatkiller IV block on a loop with a EKWB D5 and Hardware Labs GTX 420mm+280mm.
24hrs Prime95 Blend w/ AVX...peaked at 260w+:
https://imgur.com/TUSX1Il
Pics...