Well... the server died twice again last night. Very annoying! I've decided that as it's not Arctic temeratures, and it therefore shouldn't be the temperature that's directly killing components, that it could be something that isn't seated correctly contracting and causing a bad contact... or something like that.
The upshot of this is that later today (if I'm not too busy) I'm going to bring the server through the hole in the wall, into my room and take the whole bloody thing apart... and then put it back together again removing any dust and what have you. Might work... might not. Worth a try though, as the BEEEP when it resets wakes me up at night!