Physical temp diode under cpu

[t4runnr]

I was just wondering if anyone knows how close the temp of the surface under the cpu diode is to the cpu diode temp.

Would the difference be as much as the difference that most suggest between the socket temp and the diode temp?

I was thinking of putting one under the cpu since my NF7-S board does not seem to have a diode reading in MBM5. At least one that I can tell. I could be wrong.

Any help would be appreciated.

Thanks

 

[MisterEd]

MBM5 uses these readings for the NF7-S:
Case Sensor = Winbond 1
CPU Sensor = Winbond 2 (CPU socket)
Note: Winbond 3 is not hooked up to antything!

The CPU diode temperature is measured but is not hooked to Winbond. It us used by the thermal protection system for the motherboard. Here is a mod that disconnects the CPU diode connection and hooks it to Winbond 3 so MBM5 can show it. The usual warning goes that you mod anything at your own risk.

NF7-S CPU Thermal Diode Mod
http://www.aoaforums.com/forum/showthread.php?t=23468

 

[TheNewbie]

It depends on the load the cpu has at a given time. Mine is usually pretty close the diode and socket at idle but under load it can be as much as 10c diffrence (diode hotter).

 

[t4runnr]

MisterEd, thanks for the info and that link. I'll try that, eventually. =P

TheNewbie, thanks for the reply but I already understand the difference between idle and load. My question was if the surface directly under the core at the bottom of the cpu is closer to socket temp or diode temp, regardless of idle or load.

 

[MisterEd]

I was just wondering if anyone knows how close the temp of the surface under the cpu diode is to the cpu diode temp.

Would the difference be as much as the difference that most suggest between the socket temp and the diode temp?

I was thinking of putting one under the cpu since my NF7-S board does not seem to have a diode reading in MBM5. At least one that I can tell. I could be wrong.

Any help would be appreciated.

Thanks

I guess I should answer your question more directly. You seem to be confused about what the socket temperature is. The socket temperature is gained by the motherboard manufacturer placing a diode under the cpu in the socket. There is no need to add a diode because your motherboard already has a diode under the cpu in the socket. MBM5 can read the temperature from the socket diode.

Your CPU also has the internal diode. The CPU diode temperature is used by the thermal control system but is not available to MBM5. It can be made available to MBM5 if you make a mod.

To summarize:
CPU socket temperature = temperature from diode in socket under CPU
CPU diode temperature = temperature from diode internal to CPU

As to the difference between the two temperatures it depends upon a lot of factors including the CPU type and the effectiveness of the cooler. It is not unusual to see a 10C difference. Here is an example from my system:

ASUS A7N8X Deluxe w/Athlon XP2800+

Cooler: Taisol CGK760172
Case: 41 C
CPU Diode: 64 C
CPU Socket: 51 C
Cooler Fan: 5100 RPM
Noise Level: 36 dB
Weight: 264 grams

Cooler: Zalman CNPS7000A-Cu
Case: 41 C
CPU Diode: 47 C
CPU Socket: 39 C
Cooler Fan: 2280 RPM
Noise Level: 25 dB
Weight: 773 grams

 

[t4runnr]

I understand completely what socket and diode is. But the Abit NF7-S diode cannot be read with MBM. At least not until you posted that link to mod the board.

 

[TheNewbie]

Well if it is directly under the core then I would think that it would be alot closer to diode temp than the socket temp. Common sense would tell me if you move closer to the fire you will feel more of the heat.

 

[MisterEd]

First let me make a correction. The temperature sensor in the socket is actually a thermistor not a diode like I said. A thermistor is a temperature sensitive resistor. This thermistor is located in the open area in the socket. It extends upwards enough to touch the CPU bottom when it is placed in the socket.

The reasons why the diode inside CPU is used instead of the socket thermistor for thermal protection probably are:
1. If for some reason the thermistor did not touch the CPU then it would give erratic readings possibly shutting down the computer needlessly
2. The cpu diode being close to the core gives more accurate readings
3. The cpu diode reacts faster to CPU temperature changes

Here is a picture of the socket thermistor. It is the blue thing inside the socket.

Picture borrowed from this source:
Abit NF7-S Motherboard Review
Review Date: April 16, 2003
Reviewed By: John LeVan
http://www.pcextreme.net/nf7-s3.php

 

[t4runnr]

Well, thanks for the info. Not sure if it answered my original question but that link you provided sure did. I will definitely give that try so that MBM can read my diode on my board. Then I wouldn't have to worry about putting a thermister under my cpu.

Thanks again for that link.