RTX 5090 usage issues

I think Resolve20 doesn't optimize RTX5090 very well.
My graphics card driver version is: 576.52
The graphics card usage is often stuck at 60% and can't go up.

There's not enough information to determine anything from that. The GPU might be waiting for data that's controlled by the CPU. The bottleneck might be an operation that isn't multithreaded. There could be any number of reasons. A controlled test environment would be needed to make any sort of determination.

Same, i have very powerful machine and 5090 almost 2x slower on the final render then my 2x4080 Super, although it should be roughly about the same performance. More precisely, it is slower in tasks with effects, for example, face refinement.

Is the card in a PCIe 5.0 x16 slot? Although it is backwards compatible, you need a PCIe 5.0 motherboard to get the full bandwidth the card is capable of. If on a PCIe 5.0 motherboard, make sure the slot isn't configured for x8/x8 as you might have had it when running the two 4080s.

My computer is Supermicro SuperWorkstation SYS-551A-T
CPU: Intel® Xeon® W9-3495X
RAM: 128Gb
System hard drive: 4T SSD
Graphics card: ZOTAC RTX 5090
Storage: : Accusys A16S3-PS 96TB

Originally I used RTX 4090, but recently I upgraded to 5090. However, the speed is obviously slower under Resolve 20.
I also reinstalled the graphics card driver and Resolve 20, but the Optimizing Davinci Neural engines did not appear.

Ok, being slower than the older card is interesting.

With the release version of DaVinci Resolve 20, the separate optimization step is no longer needed.
Source: https://forum.blackmagicdesign.com/viewtopic.php?f=21&t=222420&p=1153523#p1151571

Originally I used RTX 4090, but recently I upgraded to 5090. However, the speed is obviously slower under Resolve 20.
I also reinstalled the graphics card driver and Resolve 20, but the Optimizing Davinci Neural engines did not appear.

Did you use the betas where the neural engine optimisation had to be performed, were the speeds as you expected then but have become slower with the release version or has the 5090 always been slower than the 4090?

What speeds do you get with Magic Mask2, one 5090 user was getting 30fps when tracking on Better setting, I don't know if it matters but use a tracking example that requires only 2 points to mask your object?

Without other effects, the maximum frame rate of magic mask is 28fps.
If there are other effects such as motion effect and glow,
it can only be 9fps.

Yeah, Resolve 20 seems to underutilize the RTX 5090. I’ve tried different drivers and settings - no major difference. Might just be a matter of software catching up with the new hardware.