Have you tried to take out the video card and wipe the contacts on it with an eraser? And reinstall the drivers completely? With the help of amd uninstall utility and reinstall, preferably with a reboot and disconnected Internet, well, and a downloaded draver that you will install)
Alternatively, try downloading a driver for your video card for your windows 11, then using Display Driver Uninstaller to remove the driver, but select installing a new video card, in this case the PC will turn off, and then take out the video card, wipe the contacts with an eraser and reconnect (do not forget about additional power) and preferably disconnect the Internet or simply remove the cable when you turn on the PC, and then manually install the downloaded driver, perhaps the driver or the system did not initialize the video card correctly. Post about the results)
i found the problem it was the card it self there was traces on the pcie that had been cut or not making contact on the card so it wasnt getting the full 16x lanes. contact amazon to send me a replacement one.
one thing was odd was my 5700xt is pcie 4.0 16x card and it ran at 3.0 x16 lanes with no issues. i figure it had to be the card it self. because i have only one other pcie card it its in a pcie 1x slot and there nothing else beside the graphic card. so i put my 5700xt back in for until i get the replacement one. one thing i did was what other people have try nothing was working.
This is actually a fairly wide spread issue with Vega 5000 and 6000 series GPU's on Windows 11.
Most of the people I've checked on report running Asus Asrock or Gigabyte MOBO's
I went on YouTube and typed in problems with windows 11 PC's throttling AMD GPU to 8 pipelines. Wow their is a lot of them.
Some Intel and MSI MOBO users have reported similar occurrences it's even affecting Invidia 2050 2060 and 3050 and 3060 GPU's
I'm just tossing out a guess but it sounds like Microsoft could be the main problem.
Doesn't mean we won't be able to find a workaround and get your PC to full throttle.
Yes, maybe the card was used. and there was such a strange defect, which, in fact, if you don't check and you won't find out. If you use pci express 4 versions, even x8, then there should be no problems, but in version 3 of x8 there will definitely be problems if the rx 6600 has a drop in performance using pci express version 3, and it works at most x8, in tests with version 4 of pci express, performance is good.(there is enough bandwidth) even on x8. And in other cases, you need to look at the processor, since some amd processors with integrated graphics do not pull x 16, but you need to look at the specification for the processor, you have a motherboard of version 3 and x 16 should work, but the processor supports version 4 x 16. I hope they will exchange your card or refund your money.