BSODs during long periods of activity, 4-5 hours.

[Ttone]

I just started having bsods on a brand new harddrive (and 8 gb ram) that replaced a bad one. Recently, the bsods happen randomly after about 15-30 minutes of activity and have changed to just black screens, then restarting the boot process.

 

[Ttone]

New Dump

 

[callumm]

Hello

You are getting a 0x124 Bugcheck

BUGCHECK_STR:  0x124_AuthenticAMD

These are usually related to hardware. AuthenticAMD seems to be your processor.
I would suggest running a Prime95 CPU Stress Test.
*Please read this before - http://www.sevenforums.com/tutorials/100352-hardware-stress-test-prime95.html *

Please post results form that. (See if it BSOD's)