Q9550 Temperature Questions


May 21, 2009
Okay, I have an everest for OC testing. I'm confuse because Everest shows a CPU temp and 4 more individual temps. Are these related? What is the most important the Main CPU temp or the individual core temp? thanks


Intel Master

Yes, CPU temperature and Core temperatures are closely related. When properly calibrated, Core temperatures are 5c higher than CPU temperature, and CPU temperature is always higher than ambient temperature. Never expect uncalibrated processor temperatures to be accurate.

According to Intel's Thermal Specifications, cjl's advice for keeping Core temperatures under 72 - 73c is off by just a few degrees, however, he's correct in that Prime95 Small FFT is the standard test for thermal benchmarking. To answer your question, BOTH temperatures are relevant, as I will explain.

Intel's Thermal Specification for your Q9550, whether C1 or E0 Stepping is 71c, which is shown in their Processor Spec Finder - http://processorfinder.intel.com/details.aspx?sSpec=SLB8V This means CPU temperature, NOT Core temperature, which is a very common misconception among many users.

There is a 5c gradient between CPU temperature and Core temperatures, which is shown in the following Intel document - http://arxiv.org/ftp/arxiv/papers/0709/0709.1861.pdf This means that the corresponding Core temperature is 76c, as follows:

Maximum CPU temperature (Tcase Max) 71c + 5c = 76c Core temperatures.

Q9550 specs:

CPU (Tcase Max) 71c
Core (Tjunction) 76c
Vcore Max 1.3625

Intel has stated that the Core temperature sensors (Digital Thermal Sensors) are designed for overtemp protection only, such as Throttle and Shutdown near 100c (Tjunction Max), which would correspond to a CPU temperature of 95c, and is far too hot for sane operation. Intel has further stated that the Core temperature sensors become less accurate as temperatures decrease, and may "stick" below 50c on 45 nanometer Core 2 processors (such as your Q0550), and should be regarded as unreliable at idle temperatures.

Unlike the Core temperature sensors, the CPU temperature sensor (Analog Thermal Diode) was designed to be linear from low idle temperatures thru high load temperatures. This is why motherboard manufacturers, as per agreement with Intel, support CPU temperature, but not Core temperatures in their monitoring utilities (such as Asus Probe) which is included on the Installation CD.

For your Q9550, CPU temperatures above 71c and Core temperatures above 76c should be regarded as an "overtemp" condition.

If you'd like to learn more about how processor temperatures work, or how to calibrate your temperatures, then check out the Sticky at the top of this Forum: Core i7 and Core 2 Temperature Guide - http://www.tomshardware.com/forum/221745-29-sticky-core-core-temperature-guide

Comp :sol: