Recently put together my i5-2500K build. At first I didn't think of overclocking really because I was just using the stock cooler, but I checked and compared my temps and they were very low compared to others using the stock cooler probably because my case has great airflow. So I decided to overclock it a little bit to 4.0 GHz and the temperatures barely increased, only by a few degrees. I thought overclocking on the stock cooler was a bad idea but it still runs pretty cool. It stays at or below 35C at 4 GHz for all 4 cores - that seems strange to me. Also, is it fine to leave off the Turbo Boost and SpeedStep to just run it at 4.0 GHz constantly?
Yeah, that sounds like an idle temperature. Run prime95 for a while and check the temps. But yes, it's fine to run it at that speed all the time, and probably significantly faster than that too. A 965 can hit 4.0; a 2500k should get much farther with no problems.
Idle temps are mostly meaningless. At stock 3.4 ghz, my i7 2600K idles around 27 C. At 4.6 ghz, it idles at...........about 27 C also. Reason being is that the frequency will mostly be the same under power saving mode when idling
The load temps are what is important. Run it on Prime 95 for an hour or so to get an idea of what your stress temps are