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Gigabyte GA-EP45-UD3P system temperature?

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June 27, 2009 12:54:51 AM

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.
June 27, 2009 2:58:27 AM

hecto said:
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...

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
June 27, 2009 3:00:23 AM

Oh wait. You said System Sensor is reading 50 C. That is the Tjunction value so Tcase should be 5 C less. You are right on the money. :-)

Mike Ramsey
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June 27, 2009 4:23:15 AM

I don't believe that System is a Tjunction sensor, because I can see in SpeedFan the individual core sensors at 10 C above CPU. The System sensor is still listed separately at 20 C warmer than CPU.
June 27, 2009 4:57:33 AM

hecto said:
I don't believe that System is a Tjunction sensor, because I can see in SpeedFan the individual core sensors at 10 C above CPU. The System sensor is still listed separately at 20 C warmer than CPU.


I went to Intel's home page and found this:
http://www.intel.com/support/motherboards/desktop/sb/CS...

"... monitors system temperature in several different zones on the desktop board.

* Processor Zone: monitors the processor; the thermal diode is on the processor itself.
* Zone 1 or Zone 2: (may also be referred to as the motherboard zone); monitors the area around additional remote sensors. These locations are dependent on board model.
* MCH Zone: monitors the area around the Memory Controller Hub (MCH)
* ICH Zone: monitors the area around the I/O Controller Hub (ICH)"

It would help to know which zone is running hot. Also what version of the monitoring software you are using. I am assuming (because I can't see what you are seeing) that you are looking at the Intel monitoring programs results.

For Zone 1, Zone 2, or Motherboard Zone 50 C is the default threshold setting to trigger an alarm for some of the older monitoring software versions. For the processor zone 75 C is the default trigger.

Let us know what you find out.

--Mike Ramsey
a c 177 V Motherboard
June 27, 2009 5:48:46 PM

This is from an old post at TweakTown by their resident GB tech rep - it was in a discussion of how the various fan headers work:

Quote:
SYS_FAN2 connector needs any fan, with three or four wires (don't care) since the speed is controlled via on-board PWM controller that supply pulse-width-modulated 12v for the fan via pin 2.
So, if using a four wire fan, its internal PWM is locked to full speed (this explain that fixed 5v on pin 4).
This time, the mobo senses the North Bridge (in my case the P35) temperature and will increase or decrease the speed of the fan connected in this socket. Feedback is sent to pin 3 for BIOS alarm purposes.


Other discussion inferred that the relevant sensor, on the 'd' series boards anyways, is somewhere near the end of the second PCIe slot, in the 'general vicinity' of, but not directly under, the northbridge. This has always been a vague subject, and if anyone could somehow add some clarity to it - it would be an invaluable service to everyone!
!