Progress update! While I haven't tried anything stressful ingame recently, I've managed to finish the SHB benchmark without crashing. All I've done since then is crank the fans to 95% and relocated the tower to sit on its side on a desk. Tried this a few times to then tried it without the fan and it crashed in the third cutscene. I've tweaked so many things at this point I could be forgetting something. Guess all this points to overheating, but I'm not sure how to fix that more than I already have without opening the tower. I'm not sure if I can rely on it for say farming e6s (it used to crash so badly in phase 2) but I'll be looking into how it handles ingame stuff coming up.