Guys I found some interesting explanation about TAT and Bios readings.
This is a composite of my response on similar threads...
Many posts which describe "load" temps may not be aware there are 2 distinct C2D thermal specifications, and don't define which programs were used, and don't realize that Prime95, Orthos, Everest, and assorted tests use intermittent loads, or loads less than 100%. These are great for stress testing CPU, memory and system stability over time, but aren't ideal for testing CPU cooling efficiency. Consequently, there is considerable confusion concerning differences in results, so further explanation may help to level the playing field.
Here's Intel's Thermal Specification as per the following link:
http://processorfinder.intel.com/details.aspx?sSpec=SL9S8Thermal 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(R) 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 references a single measuring point, which would be in contact with the CPU cooler, via the heat sink compound. Since there is no sensor at this point, BIOS temps are indicated from CPU look-up tables, referencing Intel's spec for Thermal Case Maximum (Tc max) on the TM2 sensor, (motherboard CPU socket temp sensor) to calculate this single measuring point. Additionally, one core always runs hotter than the other, so this calculated measurement is at best, an average value, and is an approximate redline. 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
The second part of the spec refers to mobile CPU's measured at the TM1 Thermal Junction sensors (Tj) with Intel's Thermal Monitor (TAT), which is a Notebook tool. This is why TAT indicates slighty lower on PC's than Core Temp, which correctly displays Intel's spec for Thermal Junction Maximum (Tj max) as 85c. This is an absolute redline limit. 75c is hot, 80c is overtemp where TAT reaches red-line and throttling begins, and 85c is shutdown. These are the dual core temps displayed in Intel's Thermal Analysis Tool (TAT) and Core Temp.
All C2D's - 85c
Obviously, there are some calibration and specification ambiguities here. The temperature differences between BIOS, OEM monitoring utilities and SpeedFan, versus TAT and Core Temp is approximately BIOS + ~ 15c = Core Temp. Intel's Thermal Analysis Tool (TAT) should be used for thermal testing C2D's at 100% continuous load, and Core Temp should be used simultaneously for measurements.
TAT:
http://www.techpowerup.com/downloads/392/mirrors.phpCore Temp:
http://www.thecoolest.zerobrains.com/CoreTemp/Note: SpeedFan Beta 4.32 reads TM2 and TM1 sensors:
http://www.almico.com/speedfan.phpTAT will expose insufficient CPU and case cooling, just as ATI Tool "Show 3D View" tests GPU cooling at 100% continuous load. At no other time will a PC be so heavily CPU loaded, even when highly OC'd during worst-case / real-world loads. The 65W Thermal Design Power (TDP) spec is exceeded by a considerable margin when Vcore and CPU frequency are increased, so 50c BIOS and 65c Core Temp at 100% TAT are safe and reasonable thermal values.
The temp scale shows the range between idle and TAT load, and illustrates the typical ~ 15c offset seen in the following example:
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 results from my rig are defined as:
Load = TAT @ 100% continuous
Temps = Core Temp @ highest core
3.7Ghz
1.5125 Vcore
36c Idle, 52c Load - BIOS
51c Idle, 67c Load - Core Temp
I hope this helps to make sense of CPU temp alphabet soup.
2) the thermal spec by intel should be used in reference to the temps reported by bios or the TM2 sensor (for e6300 its 61.4c)
3) For TAT or coretemp temps, ure ultimate max would be 85c. 75c is hot, 80c is overtemp where TAT reaches red-line and throttling begins.