Quote Originally Posted by Praz View Post
Those results may be a bug in Prime95. It did the same thing when one core would fail. After I brought this up the issue was fixed in v25.6.
I was using version 25.6 in that screen shot. It's not a bug in Prime, just the way Quad core and Dual Core processors balance the load. The same thing happens when you have a Dual Core and run 1 instance of Prime. The CPU will constantly swap the task back and forth between cores to keep the cores balanced and core temperature seems to play a big part in that decision. This also happens when you run the typical single threaded game on a Quad. It doesn't run one core at 100%. It constantly spreads the work around so each core does part of the job so no one core gets over stressed.

AndrewZorn: JohnZS may not have the record but his 45nm Quad certainly ranks highly when it comes to unbalanced sensors. On the same die he had a difference of 7 between core2 and core3 and the difference was 15 between the two dies when comparing core1 and core2. When you pull out the ruler and measure the number of millimeters between sensors, it becomes obvious that something isn't quite right.

Intel showed us that their 45nm sensors suffer from slope error where the further you get from their calibration point, the bigger the error can become. If you have one sensor that reads too high and one that reads too low on the same die then the combined error can be quite significant.



Intel did not get specific about what temperature they calibrate at but the example in the graph shows how slope error grows as temps decrease.

In my experience, most of the 65nm CPUs I've seen have had sensors on the same die that were either both too high or both too low. The 45nm Quad processors, especially some Extreme CPUs, can have both high and low reading sensors on the same die.

65nm sensors can also bottom out or get stuck at lower temperatures but this seems to be much rarer and at far cooler temperatures than some of the 45nm sensors get stuck at.

If you are water cooled then you need to be comparing your Ultra-Idle reported temperatures to your water temperature. (I like the term Ultra-Idle for low MHz / low volts.) Is there any way for you to manually set your core voltage lower in the bios? Try that and enable C1E or lock your multi to 6.0 when testing if your computer doesn't complain. My Asus boots up fine but some boards don't like to boot up when locked to 6.0x

I think a Q6600 being 5C or 6C above your water temp during this test is pretty reasonable. Open your case up and send me a log file at a 1 second interval of running 1 minute idle, 2 minutes of Prime small FFTs on all cores followed by 1 minute of idle. That helps me understand your processor better than just seeing a single screen shot.