I have googled any available piece information but did not get a confirmation on this.

Apparently, system temperature is NOT indicating the northbridge temperature, well at least not on my gigabyte GA-P35-DS3 mobo.

Due to the keen observation of one of our forumer, I have confirmed that the temperature sensor is at or near the southbridge.

When I direct a fan ONLY on the northbridge, the system temperature is static at 43'c (this is stock NB heatsink!)
When I direct a fan ONLY on the southbridge, the system temperature dropped to 41'c.....

Some sources indicate that the temperature sensor is an on-chip sensor in the ICH (southbridge) chipset.

My question:
- Does anybody know for certain what the "system temperature" is showing?
- Are there mobo's which show both system temp and NB temp?

Note : Remember that some AMD systems (which does not have a NB), also shows a NB temperature!!!!

Yes.
DFI Infinity P965-S that is.

Cool! I checked out this mobo and it is stated clearly about the NB temp : http://www.dfi.com.tw/Product/xx_product_s...TYPE=LP&SITE=US

How about current p35 mobos?

Normally system temp is refering to ambient temp of the mobo or something like that.

Most of the high end board from reputable OEM maker do show NB temp.

I wonder whether the GA-P35-DQ6 also show the NB temp?

Yes... there is...

You can double check with irenic

Already pm him. Awaiting reply. If only high-end mobos have a temperature sensor at the northbridge, I guess the sensor is not on-chip then.....

AMD systems have a NB, but no memory controller on the board as its on the CPU. What some AMD systems often don't have is a SB, as NB is usually built to handle SB functions since its primary function (memory control) is done by the CPU.