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The following is a copy of a post I made to the Abit forum on October 2, 2003:
Topic: "Intel Chipset Socket 478 Motherboards"
Thread: "Official Update for the P4 motherboards temperature issue"
PostID: http://forum.abit-usa.com/showthread.php?s=&postid=171232
Text as follows:
Abit have used the W83627HF temperature monitoring chip for the entire P4 motherboard range. The same chip and the same design is used all the way from the BE7 to the IC7. The design and specification for this item is actually a carryover from the BE6-2.
The entire P4 range of Abit motherboard models using the above hardware monitor chip has exhibited the approx 10degC offset. Other motherboard manufacturers using the *same* chipset do not exhibit the offset. This confirms the problem is not the chip or the hardware design.
People who have installed outboard thermal sensors near the CPU-HSF junction to monitor that temperature (including myself) have all shown similar temperatures when monitoring the heatsink base. These temperatures have consistently shown a 10-15 degC offset in comparison to the on-die reading.
Reading this thread, the following observations are unavoidable:
1. Users with high-grade heatsinks (such as the Zalman 7000Cu or its equivalent) are solving the shutdown-on-overheat problem by reducing their CPU *peak* temperatures below the stock overheat-shutdown trigger-point through the use of high-grade cooling.
2. Users with stock heatsinks installed in marginal cases are running into the shutdown-on-overheat problem because the on-die
*reported* temperature is exceeding their shutdown-on-overheat setting in their BIOS -- even though the true heat-output of the CPU is still in the safe-to-operate range.
The above forces the following conclusions:
1. It is *possible* that because the P4 heatsink has an integrated heat-spreader, there is a higher delta-T between the on-die thermal diode inside the CPU silicon itself and the centre of the IHS heat-transfer surface where Intel mandate the temperature of the CPU should be measured for the overheat-shutdown trigger point.
Note: The delta-T on P3 CPUs between the on-die thermal diode and the heatsink itself was 2degC to 4degC on a properly applied heatsink. This has been confirmed by extensive measurement by myself and others.
Many of us are *expecting* the P4 to have a similar delta-T between the on-die thermal-diode and the heatsink -- matching that found on the P3. This is to be expected from long-standing Intel practice. However, THIS MAY NOT BE THE CASE.
If the new heat-spreader design creates a higher delta-T between the on-die thermal diode and the centre of the IHS, then the temperatures we are reading are correct FOR A P3-STYLE FLIP-CHIP MOUNT. Intel's own documentation does not make a distinction here -- nor is there any clarification in the Intel documentation to confirm whether there is a difference in the thermal path resistance between P3 and P4 CPU mounts. We need Intel to confirm this one way or the other.
2. It is a known fact that the current BIOS algorithm Abit are using for the on-die thermal diode is the same one used for all their P3 motherboards.
If there is a known delta-T for the
on-die-thermal-diode-to-IHS-centerpoint -- then there is no doubt that a new thermal calculation algorithm is *required* to account for the thermal resistance in the on-die-thermal-diode-to-IHS-centerpoint pathway. Modifying the algorithm is the *only* valid way to get a temperature reading in sync with Intel's published specifications.
Final comments:
I suspect that both Intel and the other motherboard manufacturers who are showing on-die CPU temperatures in sync with Intel's published recommendations have implemented a new algorithm to accommodate the above. It would behoove Abit to follow suit.
Best I can do for now. <tm>
Bill
Topic: "Intel Chipset Socket 478 Motherboards"
Thread: "Official Update for the P4 motherboards temperature issue"
PostID: http://forum.abit-usa.com/showthread.php?s=&postid=171232
Text as follows:
Abit have used the W83627HF temperature monitoring chip for the entire P4 motherboard range. The same chip and the same design is used all the way from the BE7 to the IC7. The design and specification for this item is actually a carryover from the BE6-2.
The entire P4 range of Abit motherboard models using the above hardware monitor chip has exhibited the approx 10degC offset. Other motherboard manufacturers using the *same* chipset do not exhibit the offset. This confirms the problem is not the chip or the hardware design.
People who have installed outboard thermal sensors near the CPU-HSF junction to monitor that temperature (including myself) have all shown similar temperatures when monitoring the heatsink base. These temperatures have consistently shown a 10-15 degC offset in comparison to the on-die reading.
Reading this thread, the following observations are unavoidable:
1. Users with high-grade heatsinks (such as the Zalman 7000Cu or its equivalent) are solving the shutdown-on-overheat problem by reducing their CPU *peak* temperatures below the stock overheat-shutdown trigger-point through the use of high-grade cooling.
2. Users with stock heatsinks installed in marginal cases are running into the shutdown-on-overheat problem because the on-die
*reported* temperature is exceeding their shutdown-on-overheat setting in their BIOS -- even though the true heat-output of the CPU is still in the safe-to-operate range.
The above forces the following conclusions:
1. It is *possible* that because the P4 heatsink has an integrated heat-spreader, there is a higher delta-T between the on-die thermal diode inside the CPU silicon itself and the centre of the IHS heat-transfer surface where Intel mandate the temperature of the CPU should be measured for the overheat-shutdown trigger point.
Note: The delta-T on P3 CPUs between the on-die thermal diode and the heatsink itself was 2degC to 4degC on a properly applied heatsink. This has been confirmed by extensive measurement by myself and others.
Many of us are *expecting* the P4 to have a similar delta-T between the on-die thermal-diode and the heatsink -- matching that found on the P3. This is to be expected from long-standing Intel practice. However, THIS MAY NOT BE THE CASE.
If the new heat-spreader design creates a higher delta-T between the on-die thermal diode and the centre of the IHS, then the temperatures we are reading are correct FOR A P3-STYLE FLIP-CHIP MOUNT. Intel's own documentation does not make a distinction here -- nor is there any clarification in the Intel documentation to confirm whether there is a difference in the thermal path resistance between P3 and P4 CPU mounts. We need Intel to confirm this one way or the other.
2. It is a known fact that the current BIOS algorithm Abit are using for the on-die thermal diode is the same one used for all their P3 motherboards.
If there is a known delta-T for the
on-die-thermal-diode-to-IHS-centerpoint -- then there is no doubt that a new thermal calculation algorithm is *required* to account for the thermal resistance in the on-die-thermal-diode-to-IHS-centerpoint pathway. Modifying the algorithm is the *only* valid way to get a temperature reading in sync with Intel's published specifications.
Final comments:
I suspect that both Intel and the other motherboard manufacturers who are showing on-die CPU temperatures in sync with Intel's published recommendations have implemented a new algorithm to accommodate the above. It would behoove Abit to follow suit.
Best I can do for now. <tm>
Bill
