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FAQ: Core 2 Duo Temp Guide

post #1 of 3
Thread Starter 
C2D Temperature Guide

Intel has 2 distinct C2D thermal specifications, and provides a test program, Thermal Analysis Tool (TAT), to simulate 100% loads. Many users may not be aware that Prime95, Orthos, Everest and assorted others, may simulate loads which are intermittent, or less than 100%. These are great for stress testing CPU, memory and system stability over time, but aren't ideal for testing the limits of CPU cooling efficiency.

Obviously, there are some specification and calibration relationships which can be difficult to interpret and understand. Consequently, there is considerable confusion concerning differences in C2D thermal testing methods and results. When describing "load" temps, it's important to define the variables, such as which programs were used at what ambient room temp, so further explanation may help to clarify these issues.

The following link is to Intel's Thermal Specification:

http://processorfinder.intel.com/det...px?sSpec=SL9S8

Thermal Specification: The thermal specification shown is the maximum case temperature at the maximum Thermal Design Power (TDP) value for that processor. It is measured at the geometric center on the topside of the processor integrated heat spreader. For processors without integrated heat spreaders such as mobile processors, the thermal specification is referred to as the junction temperature (Tj). The maximum junction temperature is defined by an activation of the processor Intel® Thermal Monitor. The Intel Thermal Monitor’s automatic mode is used to indicate that the maximum TJ has been reached.

The first part of the spec refers to one measuring point on the integrated heat spreader, which is in contact with the CPU cooler. Since there is no sensor at this location, the Socket Thermal Monitor (TM2) is used to display the CPU temp in BIOS, which stores Intel's look-up tables for Thermal Case Maximum (Tc max), to estimate a single external measuring point. This represents an average value between dual cores operating at unique temps, and is at best, an approximate limit. This is the temp displayed in BIOS, OEM monitoring utilities, and SpeedFan.

X6800 - 60.4c
E6700 - 60.1c
E6600 - 60.1c
E6400 - 61.4c
E6300 - 61.4c
E4300 - 61.4c

The second part of the spec refers to mobile processors without an integrated heat spreader, measured at two internal Junction Thermal Monitors (TM1). Since Intel's Thermal Analysis Tool (TAT) is a Notebook tool, and desktop C2D's have an integrated heat spreader, Core Temp compensates ~2c higher, and shows Intel's spec for Thermal Junction Maximum (Tj max) as 85c, which is an absolute limit. 75c is hot, 80c is overtemp where TAT reaches redline and CPU throttling begins, and 85c is shutdown. These are the dual core temps displayed by TAT, and by Core Temp.

All C2D's - 85c

The temperature differences between BIOS, OEM monitoring utilities and SpeedFan, compared with TAT and Core Temp is approximately BIOS + ~ 15c = Core Temp. Intel's Thermal Analysis Tool (TAT) can be used simultaneously with Core Temp for thermal benchmarking desktop C2D's at 100% continuous load.

Intel's Thermal Analysis Tool (TAT): http://www.techpowerup.com/downloads/392/mirrors.php

Core Temp: http://www.thecoolest.zerobrains.com/CoreTemp/

SpeedFan Beta 4.32 (reads TM2 and TM1 sensors): http://www.almico.com/speedfan.php

Intel's spec for Thermal Design Power (TDP) is 65 watts, and can be exceeded by over 50% when CPU frequency is aggresively overclocked, and Vcore is increased to maintain stability. Intel's spec for Vcore max is 1.3525, and when increased much beyond 10%, or 1.488 Vcore, safe temperatures become difficult to maintain with air cooling.

Every CPU is unique in it's overclock potential, voltage response, and thermal behavior. Whatever the stable overclock frequency is at 1.35 Vcore, each increase of .05 volts will typically allow a stable increase of ~ 100 Mhz, and will result in a cooresponding increase in CPU temperatures of ~ 3c.

For example, if a C2D is stable at 3.0 Ghz - 1.35 Vcore - 40c BIOS / 55c Core Temp @ TAT 100% load, then it may also be stable at 3.3 Ghz - 1.5 Vcore - 50c BIOS / 65c Core Temp @ TAT 100% load, with highly effective CPU and case cooling. Generally, once the maximum stable overclock is known at 1.35 Vcore, then ~ 300 Mhz of additional overclock remains until safe temperatures are exeeded due to increased Vcore.

TAT will expose insufficient CPU and case cooling, or excessive Vcore and overclock. At no other time will a CPU be so heavily loaded, or display higher values in Core Temp, even when highly OC'd during worst-case / real-world loads. After CPU thermal behavior has been benchmarked by TAT and Core Temp, then Orthos or assorted other programs can be used with Core Temp, to observe less extreme CPU temps, while stress testing for system stability.

The temp scale shown in the example below illustrates the normal ~ 20c range between idle and TAT @ 100% load, and the typical ~ 15c difference between BIOS and Core Temp. 50c BIOS and 65c Core Temp with TAT @ 100% load are safe and reasonable thermal values.

BIOS/CoreTemp
-60--/--75--75-
-55--/--70--70-
-50--/--65--65- Load
-45--/--60--60-
-40--/--55--55-
-35--/--50--50-
-30--/--45--45- Idle

The following variables and results are defined as:

Frequency = 3.6 Ghz
Vcore = 1.4625
Load = TAT @ 100% 15 minutes
Core Temp = highest core (slight differences between cores are normal)
22c = ambient room
33c Idle, 49c Load = BIOS (OEM monitoring utilities, SpeedFan)
48c Idle, 64c Load = Core Temp
post #2 of 3
Post on 2/3/07 with 30,000+ views with no replies...

Thank you for the Temperature Guide:)
post #3 of 3
I know this is years old, but still relevant. Thanks for the original post, and for leaving it up.

Im running a core 2 Duo E5200
2GB Kingston HyperX 1066 memory
Gigabyte GA-EP45-UD3P mobo F10 bios
ATI HD2600XT stock air cooled
650 watt psu

Custom CPU water cooler loop.
Black Ice II or III, its been a while
Apogee GT CPU block
Swiftech mini res.
AC submersible pond pump
Danger Den pump relay
Danger Den Fill port
1/2' ID 3/4' OD tubing
Cat Red waterless coolant

Chenming 901 full tower modded to mount motherboard top left and the entire water cooler is contained in case.



I used this 5ish year old guide to recently re-tune the system. It had been running @ 3.06ghz for years, never hitting more than 38C under gaming load (4 hour stretches). After utilizing this guide I did a mild voltage increase and bumped it to 3.33ghz. Idle tepms 43C, Load @ 49C with Ambient room temp @ 20C. The ram is running at specified 1066, an issue many many people had was getting HyperX chips to run above 800. This is cured by changing the stock mobo DRAM V+ to 2.2V from 1.8V.

When I started this build I had a few restrictions, and alot of expectations. My primary hold up was of course free cash to toss out for a toy! lol I knew it 1. Had to last a while, 2. be powerful enough for gaming the available stuff, but also todays games(6 yrs later) 3 It had to be freely OC friendly and utilize the extra HP well. 4.I knew to protect the investment and gain as long a life as possible it had to be liquid cooled.

When the E5200 hit 4ghz with a gigabyte board, my decision was made. I started the build in 2006, and have never regretted the parts combination. It plays BFBC2, CS:S, CS:GO very well, though it could use a graphics card for future games. Not bad overall, the machine has far exceeded my expectations.
Frost
(13 items)
 
  
CPUMotherboardGraphicsRAM
E5200 Wolfdale GIGABYTE GA-EP45-UD3P 2 x HD 2600XT crossfired for now Kingston HyperX 2gig 1066 
Hard DriveOptical DriveOSMonitor
robbed from junk pile 2 x 120 gb HP DVD r/rw lightscribe XP pro sp3 Dell 19 in widescreen 
KeyboardPowerCaseMouse
usually a ZBoard, might switch primary X-Power pro 650w. Secondary MGE 450w Chenming 901 Mod called Frost MX518, OCZ Equalizer 2600 dpi laser 
Mouse Pad
Teflon coated steal pad with rubber backing 
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Frost
(13 items)
 
  
CPUMotherboardGraphicsRAM
E5200 Wolfdale GIGABYTE GA-EP45-UD3P 2 x HD 2600XT crossfired for now Kingston HyperX 2gig 1066 
Hard DriveOptical DriveOSMonitor
robbed from junk pile 2 x 120 gb HP DVD r/rw lightscribe XP pro sp3 Dell 19 in widescreen 
KeyboardPowerCaseMouse
usually a ZBoard, might switch primary X-Power pro 650w. Secondary MGE 450w Chenming 901 Mod called Frost MX518, OCZ Equalizer 2600 dpi laser 
Mouse Pad
Teflon coated steal pad with rubber backing 
  hide details  
Reply
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