Every time you run a benchmark you get a different result. Sometimes, it can be night and day.
Similar to other VGA benchmarks, Port Royal is HIGLY temperature sensitive, long story short, if the card is cool, you have a higher frequency, more FPS hence higher score.
When OC-ing, once you find some stable values for power, voltages, frequencies etc it's always good to have some restarts before benchmarking, even shut down for a while your system.
I would run no later than W10 to have good results in benchmarks. Some tweaking (high performance profile, improving responsiveness etc) is also welcome.
Also, some basic settings in NVPanel are quite important for Port Royal, especially high performance for power management and textures.
It's also a good practice to update again your bios when installing a new VGA card.
That was the best stuff I could squeeze from my 3090 keeping its default AiO cooling:
https://www.3dmark.com/pr/1438721I also had Apex XIII and 11900K.
XIII & 10th was an epic fail, since bios was mostly optimized for 11th and 10th was not a priority at that time.
11th was stable, but not that good in games and VGA benchmarks compared to 10th.
XIII & 11th is a dream indeed for DDR4 overclocking but in gaming in general it was a worse experience than 10th and Z490.
The cross combinations XII & 11th and XIII & 10th were pretty garbage compared to 10th & Z490, which is why I'm still using this for my daily / gaming rig.