I think this is mostly being blown out of proportion, at least for the 30 series. I can’t speak for AMD as I haven’t looked at very many of their coolers, but anyone else is free to do so.So Asus TUF and NV refference models are confirmed to work in that orientation. I have linked this thread in many places, please - if anyone have bought Alta F1, post your resoult here, specially with GPU temps. It looks like nobody care about this issue, and its gonna be the only database for future Alta F1 and GPU users combined.
Thank You Mythras for detailed info!
The Strix was always going to be problematic, being that five of seven of its heat pipes bend above the heat source as evidenced in the Techpowerup link below. The only other models that I believe had the potential to be problematic due to their heat pipe orientation are the Asus TUF and the Evga XC3, because they have a few pipes that bend above the heat source. That said, we can check off the TUF as seen above and we’re down to what would seem to be a single model.
I’ve tested the Evga 3080 FTW3, which produced identical temperatures in either orientation, and the 3080 Hybrid FTW3 in my sig obviously doesn’t have any issues. I can’t say with certainty, but all the 30 series coolers from MSI, Giigabyte, and Zotac look like there won’t be any problems as none of the heat pipes bend above the heat source when mounted in a case like the Alta F1.
Edit - Took a peak over at r/sffpc and there are tons of people with XC3 cards in a NZXT H1. Needless to say, temperatures look unaffected from orientation and similar compared to what I've seen elsewhere in typical SFF cases.
TPU link - https://www.techpowerup.com/review/asus-geforce-rtx-3090-strix-oc/2.html