The problem lies in the fact that the vRAM is erroneously hitting it's power limit & thusly the whole card is showing power limited when it's not actually hitting 500W. If you don't believe me, try underclocking your vRAM by -250MHz & witness how much more stable & higher you can go on your GPU Core clock before hitting PWR PerfCap. It's actually kinda ridiculous, I've seen up to 489W power draw while underclocking the vRAM & OC testing the core, in TimeSpy at least. With the vRAM at stock, I can't get higher than around 473W, and only in that test, almost every game/benchmark besides that doesn't go much past 450W no matter what I do, unless I underclock the vRAM.
For now I'm still running my OC/undervolt of 2040MHz @ 1000mV on the core, it's completely stable in Cyberpunk 2077 for hours of play, and results in cooler than stock temps, with better than stock FPS, and I rarely see power limit as a )PerfCap reason due to the lower power draw by undervolting.
For reference, at stock, the 3090 FTW3 Hybrid typically boosts to 1890-1935MHz depending on temperature etc, usually sitting right around the 1920MHz mark, so my settings are basically a 120MHz OC (or stock clocks on a Kingpin card), with only 1000mV to the core, instead of the 1058-1075mV stock runs at.
Pretty sure almost every 3090 FTW3 Hybrid should be able to run 2040 @ 1000mV, so I highly recommend giving it a try... if it's unstable, bump it down to 2025MHz.
Speaking of Undervolting, has anyone noticed that even if you save a profile in Afterburner, the clock setting can randomly change itself after rebooting sometimes, and even occasionally while Windows is running, resulting in you having to re-set the MHz/voltage curve to get it at what you want it to be at again? I think this is an unfortunate bi-product of Afterburner's Ampere support still being in "beta".