You mention several SSDs. Are you using a shared M.2 slot?

Some motherboards can have M.2 slots that share pci lanes with the GPU slots. If they are used, it will SEVERELY cut down on the PCIe lanes allocated to the GPU. Make sure this isn’t happening.

Does your monitor support VRR?

Your setup should deal quite nicely with almost anything, so unless the performance problem is software-related, I’d just go straight for a more powerful GPU.

But, the 6800 is perfectly adequate, and buying a GPU sucks atm. So to improve your experience, I’d look at making sure the right amd driver is in use, that resizable bar is enabled in your bios, that you don’t have a thermal issue, and getting VRR going if you haven’t already.

Completely eliminating FPS ever dropping below a desired rate is near-impossible except by significantly exceeding the system requirements to get the FPS you want 99% of the time. You’re always gonna have those 1% moments in games where there’s just too much on-screen for the rendering to keep up. VRR makes sure you feel those drops as little as possible.

If you’re already using VRR, and are sure you don’t have a software problem, only then would I look at a GPU upgrade.

But, if you aren’t using VRR, consider getting a monitor with FreeSync (If you don’t already). IMO it has a much better cost/benefit ratio in terms of the actual gaming experience, than simply going overkill on the CPU and GPU.

You could also try overclocking your GPU. LACT is the linux program you want for fiddling with AMD GPUs. It can tell the resizable bar status and control the fans, too.