CPU/GPU question

[MeeLee]

For Windows you only need 2 threads (1 for the GPU, and 1 for the OS).
For Linux, only 1.
So you can easily disable threads you don't need, and it'll save you a few watts of power and a few degrees of heat.
I'm not sure how much DDR running in dual or Quad adds to the folding process on a GPU, but as long as your system doesn't use more RAM than you have installed, you can easily save a few watts by removing 2 or 3 sticks (as long as you have at least 1 stick with 4GB or more for Windows, perhaps Linux works with 2GB).

You can definitely lower the TDP of the GPU without affecting much of the performance. Not sure what you have as PSU, but most older PCs (with 350W PSU) can run 200W GPUs just fine.
If you tune them, an RTX 2060 to 2070 runs fine at 125W,
A 2070 Super to 2080 Super need more like 135-145W.
A 2080Ti needs at least 180W.

If you're not into tuning, then perhaps an RTX 2060 will be as high as you can go, and stay under the 200W rating.