hecto :
I just completed my first homebuilt system using the UD3P, Intel Q9550 and stock cooler. I noticed in the BIOS and EasyTune6 there are temperature sensors for "CPU" and "System." What component(s) is the latter actually measuring the temperature of? I am not overclocking, but the System sensor is reading 50C+ at idle, which seemed high given that the CPU is around 30C.
I happened to be researching this very question today.
See
http://www.tomshardware.com/forum/221745-29-sticky-core-core-temperature-guide
The "CPU" value is called Tcase in Intels spec. Tcase measure the temperature using a Thermal Diode centered under the Cores.
The second measure is "Tjunction" (Temperature junction) which is measured by Digital Thermal Sensors located on each Core.
" * Tjunction is higher than Tcase.
* Tcase is higher than Ambient."
"The Specification that Intel supports in the Processor Spec Finder for Core i7 and Core 2 desktop processors is Tcase Max, not Tjunction Max."
"Use CPU-Z (see Section 8) to read processor information including the Revision field below the Stepping field, then choose a Scale below which matches the CPU being tested. Scales are ordered from highest to lowest Tcase Max, according to Intel Thermal Specifications.
Scale 1: Quad
Q9550S: Tcase Max 76c, Stepping E0, TDP 65W, Idle 16W
Tcase/Tjunction- (four values because there are four cores; these are maximum values)
--75--/--80--80--80--80-- Hot
--70--/--75--75--75--75-- Warm
--65--/--70--70--70--70--Safe <--
--25--/--30--30--30--30-- Cool
I'd say that a Tcase of 50 degrees Celsius (50 C) is safe but is 5 C too high for idle. I am not an expert so read the standard for yourself. Others should be chiming in as well.
--Mike Ramsey