Has anyone noticed that their CPU runs hotter in a Slot 1 motherboard?

Asus P3B-F (Slot 1 motherboard): 65-75 degrees C

Asus CUBX (Socket 370 motherboard): 45-50 degrees C

All the other components were the same. Alpha FCPAL35 heatsink, Sanyo Denki 60mm fan at 5V.

Possible reasons:
1. CUBX is just calibrated differently and reports lower temperatures.
2. I mounted the heatsink better when I moved it from the P3B-F to the CUBX.
3. There is better airflow for the heatsink and the fan when mounted in a Socket 370 motherboard such as the CUBX.

Comments?

I have a Slot 1 Althon 700 and a socket A Duron... with the slot form factor for the CPU's keep in mind that there is a LOT more surface area for the heat to be dissapated.... There is a large heat speader to get the heat to the heatsink and even though they are run at about the same power as the socket factor there is a larger area for the device to get rid of its heat...
With the thermal diode on the Slot 1 board also keep in mind that the diodes are positioned in different positions on the board.... only P4's and the Newer althons have thermal diodes on chip...

Seems like in silencio's question, the same CPU/HSF is being used in 2 different boards -- a 370 socket board, and a slot-1 board via a slocket. Is that right, silencio?

In any case, it's really difficult to say what is really going on without more experimentation. If you have a temperature monitor like Digidoc or similar with flat temp probes that you can insert as close the the CPU core as possible then you can start to analyze.

Right now with the info you have, all you can say is "hmm, I wonder why?!"

Yes, I used the same CPU and heatsink in both the Slot 1 and Socket 370 motherboards. I used a Slot 1 adapter ("Slotket") with the Slot 1 adapter.

I was just speculating on the possible reasons why, but I was also wondering has anyone else also noticed, all else being the same, that Slot 1 runs hotter than Socket 370?

Based on the info you have, you cannot say that. Two different mobos about which you know little re- their temp measurement functions. All you can say is that they give different temp readings. That by itself tells you little about the CPU core temp especially as slockets also have their own idiocyncracies.

Many earlier slot-1 boards did not read the diode and used a thermistor sticking up next to the slot meant to make contact with the edge of the CPU core when it is plugged it, Thgey did not work very well. Asus is also known to compensate for thermistor inaccuracies by adding 10-15C to the actual reading.

So, there is little you know about slot 1 vs Slot 370 on the basis of your info. I would consider your 370 temp reading more accurate but also question whether the setup in your slot 1 boared was correct. It is the same CPU, there is no reason it would work at SUCH different temps.