[CentOS] Console priority

Hi all, A while back I vaguely remember someone posting a link to documentation on how to prioritise console access (for want of a better expression). For the life of me I can't find it in the archives or via Google; Can anyone provide a URL?

Basically, I have a remote server that thrashes (that's my theory at least) occasionally, resulting in the service (httpd/mysql) failing. When its in this state logging on to the console (serial + screen) responds with "login timeout". The only way back from this at the moment is a reboot.. If I can prioritize console access somehow and get on to the server I may find a clue as to what's causing it.

Cheers Dan