Bolt X internal dimensions

I don't know if anyone of us could give you an answer to the space required questions that you could rely on. I think we would be guessing. I refer you to DS on those issues. The Bolt is their in-house design, so they would be the authority IMHO. BTW, an air cooler doesn't blow air onto the the CPU. There are heat conducting tubes running up from the heat sink, and the fans and radiator fins cool the tubes.

The GPU question is almost equally murky just now. here's the conlusion reached at Digital Trends:

"Too soon to call"
"At the end of October 2020, before the RX 6800 is available or reviewed, it’s too early to say whether it’s better than the RTX 3070 or not. What is exciting, however, is that both cards should be competitive on all fronts. There’s the potential for the RX 6800 to be the slightly faster card, especially when paired with an AMD Ryzen 5000 CPU, but we don’t know much about its ray tracing support or what kind of performance impact that may have in supporting games.

It also doesn’t have a DLSS-like feature just yet, which gives the RTX 3070 a huge leg up in supporting games. The 3070 will also be the cheaper card, at least if it stays in stock long enough for price gouging not to be a problem. Considering how the launch of the 3080 and 3090 went, the 3070 may end up being more costly in the near future.

For now, both cards look like excellent ways to game at 4K and 1440p, with and without ray tracing enabled. If you’re on the fence and unsure which you want, wait for real benchmarks and for more ray-tracing information from AMD. The potential is there for either to be a stellar next-gen card for your PC upgrade, but it’s not clear just yet which is best."

Just Google 3070 vs 6800 for this whole article and several others. Basically, the 6800 is too new for any benchmarks that could tell the tale more completely, but they will be coming soon.