I doubt that it is your HD.

The noise is probably the fan $10.00 US

Replace the fan - and perhaps your entire power unit, (get a good one 350 or more $85.00.)

When your CPU or transformer overheats it clicks a breaker. When it resets it tries to reboot after an incorrect shutdown procedure. You may need to disconnect the power-plug to get the breaker to trip on sooner.

Temporary fix - take off the case and use a household fan to blow on the unit. See what happens for 24 hours. More than likely you are asking too much from an inadequate power-supply.

BTW - booting from the a: drive is a good precaution in avoiding a HD virus infection and trojans. (but not fool-proof, just one of many steps you should follow.)

Good Luck, and HAVE FUN!

Gargoyle