your computer shouldn't freeze
Since it didn't boot into the bios, I'd say you've got a hardware problem
It could be the motherboard bios got messed up and needs to be reset, it could be the powersupply or a hard drive or even the keyboard can cause all sorts problems.
Other hardware like memory I'd think would more likely restart the system or give a stop error, over heating might shutdown the system rather than freezing. But you might want to check if there is a shutdown temp or if the fans ok, if the temps ok, if the heatsink is conducting the heat, if there is a smell coming from the CPU or the power supply
How does it freeze ?
Is there anything on the monitor still or a corrupt display ?
What's you hard drive light doing ?
What other odd things does the system do ?
those are just a few questions off the top of my head.