Dirt2 won't get your CPU loaded anyways. You'll want to run Prime95 for checking max CPU temps and stability. Also, get a software monitor to check temps for CPU and GPU. Prime95 is also how you check stability if you do any overclocking. 1 hour run is considered stable in most circles, followed by a 24 'burn run' after your final overclock. You will never punish your CPU under normal use like Prime 95 does, that's why if it's stable for 1 hour then you should be good.