Using a Antec 900 case and Tuniq Tower with AS5 my normal Q600 (B3) temps (monitored by core temp) are around 38 idle and 55 under load. With a small OC from 2.4ghz to 3.0 my temps are around 46 idle and were at 74 after a few minutes of prime95 before I stopped it to avoid damaging my CPU. That's a really big increase in temp increase under stress. Voltages haven't been touched from stock.
From what I've read, this isn't a normal temp increase but many people now use G0 stepping. Is this normal with the B3 stepping? Have I just been unlucky to get a particularly poor part for overclocking?
With a Tuniq Tower that's too high. Re-seat the Tuniq and pay attention to the amount of thermal paste you used and how it looks on the processor, decide if you used too much or not enough. After that see what you can do to lower voltages.
Are the core temperatures pretty even? Are the temps you list with the Tuniq Tower's fan on high?
If temperatures increase beyond Hot Scale, then ~ 5c below Tjunction Max, Throttling is activated. The Digital Thermal Sensors (DTS) are used to trigger Intel`s TM1 and TM2 technologies for frequency, multiplier and Vcore Throttling within individual Cores. If Core temperatures increase further to Tjunction Max, then Shutdown occurs. Since Tcase indicates CPU Die temperature only, it is not used for Throttle or Shutdown activation, however, Tjunction Throttle temperature is ~ 95c, so Tcase would be ~ 85c, which would far exceed Tcase Max. As Tcase to Tjunction Deltas are constant, Tcase Max is always the limiting specification for temperatures.
Scale 4: Quad
Q6600: Tcase Max 62c, B3 Stepping, Tjunction Max 100c, Vcore Max 1.372, TDP 105w, Delta 10c
-Tcase/Tjunction- --60--/--70--70--70--70-- Hot --55--/--65--65--65--65-- Warm --50--/--60--60--60--60-- Safe --25--/--35--35--35--35-- Cool
You may want to follow through the calibration procedure in Section 9 so that you can use SpeedFan to monitor the more critical CPU temp (Tcase) as well as your Core temps (Tjunction). Also, check your Q6600 Integrated Heat Spreader and the Tuniq Tower Heat Sinc for flatness. A large percentage of Q6600's have been released with either convex or concave Integrated Heat Spreaders, but I have no information concerning the quality control of the Tuniq Tower Heat Sinc.