cpu fan and heatsink fail?

I got the AMD Phenom II 940 AM2+ 3.0 GHz quad core (not overclocked) with a stock fan and heatsink. I also have a new Azza case with like 5 fans total (very nice case) all on air with room temp being 28* C. I have plenty of room in my case as well for air flow. At idle I get around 43* C (lowest ever got was 41* C). But when I use prime 95 my temps skyrocket... 50... 60... 70... I finnaly turned prime 95 off when my temps got to 76* C. It took a few mins to get there but still... I think it would have gone higher. Is 76 * C to high for this? I think it is but not sure. Could there be something wrong with my heatsink or something? I have just got this cpu and heatsink yesterday. Thanks.