Well, my mobo crackled when I had it oc'ed without a HS on my southbridge, but that wouldn't make your computer crash.
What usually is the case is temperature or not enough vcore if you're oc'ing. If you have the old BIOS (3.6) w/ a Prescott, it may be reading temps that are higher than they actually are and then shutting down your computer. Are you using the stock HS on the Prescott?
BTW, have you seen a temp shutoff on this BIOS? I can't recall if it's there or not... if so, you could try changing it. I'm leaning towards heat for the shutoff b/c it happened while you were gaming, and Prescotts run really hot as it is.
Ticking.... I've never heard ticking from my mobo... my brother's mobo makes a loud humming noise when it's under load, but I can't recall ever hearing ticking. Have you tried the MSI forums yet? They might be able to help you over there as well.
Sorry about the problems you're having and I hope you're able to fix them soon.