A few years ago I built a glorified home server PC, I’m considering dropping a decent video card into it and trying to use it hooked up to a TV as a Linux running Steam machine-esque system, but I’m not sure if it’s worth it based on the other specs. I know the CPU in particular could use an upgrade, but as is should I bother dropping something like an RTX 5070 in it?
A 5070 is absolute overkill for the CPU. The cpu won’t be able to feed the GPU fast enough so it’ll be sitting there idle half the time.
A 5800xt or 5700x3d will work in that board and handle the gpu easily.