For stock that might be a bit high. The stock heatsinks are generally junk and that doesn't give you much room for overclocking. I would not want to exceed 80 degrees under prime. So the problem good have indeed been temperature but you'd have to hit nearly 100c for that to happen. You might only be able to get 4-4.2ghz out of it if your case/heatsink is giving you those temperatures. If you want more performance there are many great cheap heatsinks out there 212+ comes up as recommended the most . I still think your power supply might be suspect. Try running prime overnight and check temps in the morning.
ok thank you for that i will try it overnight I have some artic silver at home would that be ok as a heat-sink? And in lamens terms what am i actually applying the heat-sink to? Where the fan presses onto chip?