Checked out: Pentium 4 emergency shutdown

Checked out: Pentium 4 emergency shutdown

Since Tom's hardware guide posted a video on the subject of emergency shutdown and thermal management of Intel and AMD CPUs online, you have come across some hair-raising false statements in forums and newsgroups all over the Internet - we want to do a little educational work.

Also on one could often observe scenarios like this one in the last month:

Boardie A: My Intel Pentium 4 PC is really slow in games. [...] The CPU has 61 ° C under load. Boardie B: The P4 slows down when temperatures are too high. That is why your PC is so slow.

Shortly after the AVI was published by THG, we also rushed to the plan to get a little closer to the P4 with the fan deactivated in this regard and were already standing after our first attempt to walk before an obstacle: none of our Pentium 4 CPUs wanted to slow down on the two boards used (Asus P4S333 and P4B533) above a certain temperature threshold. All models continued to calculate without a brake until the emergency shutdown. However, this worked smoothly and so the CPU usually went into deep sleep at a temperature of 80-90 ° C. Incidentally, as Intel informed us, the threshold is selected individually for each CPU.

But how did THG manage to 'throttle' the Willamette without the cooler installed? Was this function removed from the Northwood core that we used for our purposes (2.0 - 2.8 GHz)?

The project came back to our minds when we looked at the Asus P4PE box . There the so-called 'throttling' is explicitly listed as a feature. Lo and behold, from a temperature of 70 ° C, the P4 began to throttle its power approximately linearly down to 30%, until it then switched off again at a temperature of 80 ° C. Try the Asus Granite Bay Board and a Gigabyte 8IEXPgave the same result.

What do we conclude from these results?

  • 1. In order for the Pentium 4 to be able to reduce its performance at all, the board must also support this function. This does not seem to be the case everywhere with older models. (Intel has now also confirmed this to us.)
  • 2. It is only throttled from a temperature of 70 ° C or slightly above. Accordingly, temperatures below 70 ° C cannot reduce the CPU's performance and should be absolutely harmless beyond that.
  • 3. The emergency shutdown works absolutely smoothly, but can vary from CPU to CPU. When idling in Windows XP without a running fan, it took a full six hours on a Pentium 4 2.0GHz until the critical mark was reached without throttling the clock. Without the heat sink installed, it takes about 15 seconds under load until the CPU switches off.
  • 4. The result presented by THG must on no account be misinterpreted. Throtteling also serves to maintain the life of the CPU when the cooling system is removed. However, the processor does not last more than a few seconds in this state - even if the video could make it appear as if Quake3Arena has been running forever. Tom's hardware guide has simply reassembled the cooler soon enough.

If you want to check out your P4 and the mainboard you are using, you can do this with the tool ' Stability Test 'do. The benchmark value displayed here is updated every second and thus offers a good overview of the drop in performance. Even if our P4 2.0GHz survived almost 25 shutdowns unscathed, any experiment is of course at your own risk ;-)