• Welcome to Overclockers Forums! Join us to reply in threads, receive reduced ads, and to customize your site experience!

P4 clock speed throttling...

Overclockers is supported by our readers. When you click a link to make a purchase, we may earn a commission. Learn More.


Dec 4, 2003
SpoCompton, Wa
Just curious if anybody knows. Is the throttling of the P4 CPU controlled internally by the chip, or at the motherboard? Is there a set temperature that this happens? Can it be disabled? As far as I can tell, my system seems to slow down once the CPU temp reaches approx 50C, but even that reading may not be accurate, because I think it's a motherboard sensor, unless it's somehow reading an internal thermal sensor in the CPU. Any info on this topic would be greatly appreciated :)
The P4 has an internal diode used for reading temps I believe that there are two, one is right next to the FPU where the most heat is made and this one is the quick trigger one that if the temp reaches a high mark it turns off saving the machine, and there is one somewhere else that clock throttles and is located in a less hot place on the silicon.
Is there any way I could tell if my motherboard and monitoring software reads an internal diode, or one mounted on the motherboard? I'm using the intel active monitor software, and using an intel d865gbf motherboard.
I think it reads both. I have a 845BG board. I am using MBM5 and the temps from that program and the ones from Intel are within 1°C of one another. My case temp right now is 77°F and reading my external thermometer's bulb which is suspended in mid case says it is 77.6°F. From other places I have read, the diode for the cpu chip is one the under side of the cpu chip itself and not on the motherbaord. This gives ir a more accurate reading.
some motherboards do monitor and throttle the CPU based on temperature readings (ASUS P4P800 for instance).

The 'C' versions of the P4 don't throttle speed any more, they shut-down the system instead. So, it's your motherboard doing it.
There is an internal sensor in the CPU for temperature readings.

I would think that you could disable these temperature "safeguards" in your MoBo's BIOS. You won't fry your CPU without it, you just won't get that annoying throttling.

I shipped a friend a system with a P4 2.4C and the heatsink got dislodged in the process. He ran that thing to temperature induced shut-down hundreds of times before resetting the heatsink and the CPU is still running strong.
The motherboard itself has a monitor but NO WAY is it controlling the P4 sensors. So there is 2 sensors

The P4 has a built in sensor that does not care anything about the motherboard and it clocks itself down once reaching a temp of 60 celcius and automatic shutdown at 70 celcius.

If its throttling down at 50celcius then maybe its your motherboard throttling because it would have to be 60 celcius for the p4 to throttle down.
The processor shut down is at 135 C. I couldn't find the throttle temperature, but I've heard it is around 70 C. Most likly, if you are having throttle problems its the motherboard, as those are usally set lower.

You can find this information about the P4 thermal monitor in this link pages 74 and 75.
I definetly know the shutdown temp is not 135 C because by then it will be fried. Do you have any reference to where you got the 135 c from?
The P4 is suppose to die at 75 C
Wow, that's a lot of really great information people. Thanks very much, guess I'll have to go into my BIOS and see if my mobo might be throttling things back the CPU, as it only seems to be maxing out at around 50C. Once again, thanks everyone for the info.
Colin said:
You may find this paper from Intel an interesting read. ;)

Wow great link and a better read, saved thanks colin :)

By using a factory tuned, precision on-die thermal sensor
and a fast acting thermal control circuit (TCC), the processor can keep its die temperature within factory specifications
under nearly all conditions without the aid of any additional software or hardware.

Ha I was right :D