Some q6600 have a little trouble reaching 3.6 let alone 4.1. You must be grossly
undervolting overvolting it for that clock speed. You will most likely need 1.55 or more on the vcore and that's low I suspect for 4.1. To prime95 stable at 4.1 on a q6600 your gonna need water or better because the voltage is gonna be high.
I suspect that you made a typo and not a real mistake.
Anything appreciably over 1.55 volts will shorten the operating life of a Q6600.