CPU Clock Speed Fluctuates and CPU runs hot.

8890 with a 3.2GHz HT, Raid 0, 2GB RAM

I just installed NHC (Notebook Hardware Control - www.pbus-167.com) and when I start it up I find that the CPU Clock Histogram indicates my CPU clock speed is fluctuating between 1.xxGHz and the correct 3.2GHz clock speed.

This is not a SpeedStep processor and I have set my power scheme to "Always On", and in NHC I have set the CPU Speed settings to "Max. Performance".

Has anybody else seen this? Does anybody have an idea why the CPU speed might fluctuate? Coud this be because of Hyper Threading? I think this explains why I have been experiencing slow response at times?

Also, my CPU has been running hot (HRC indicates 57C to 62C), at times resulting in the double flashing LEDs. I cleaned the heatsink and applied new heat sink thermal compound. What might be causing this? Could this be the reason for the clock speed throttling down?

Any help/feedback is appreciated.

Let me supply a little more detail.

It's a 3.2GHz Pentium 4 with Hyper Threading. Total of three HDDs (2 in Raid 0 configuration, third is used as a "secondary" drive). Running WinXP and lots of software. With the current behaviour, I am running MaxFan to keep the fans at full.

Thanks for the suggestion about the fans, after the behavior started I did a thourough system dissambly and took the opportunity to dismantle the fans and clean them. I did the same for the mother board fan. I used Arctic Silver Ceramique for the thermal compound, which has the same thermal characteristics as Arctic Sliver. I went to the Arctic Silver site and followed their PDF instructions on the application to make sure I wasn't missing anything.

The behavior that I am noticing only began recently. There were no system or software changes that would account for it. Previously, although the CPU did run hot, often between 55C and 60C, I never experienced the overheat warning (num & cap lock LEDs flashing in unison). When I don't use MaxFan, the fans would often run at full-tilt, but still no flashing LEDs. Now the LEDs are flashing fairly constantly, which is why I am worried.

Until the other day I did not have the NHC software, so I have no benchmarks, other than the temperature. I have never had a utility to monitor clock speed, however, I don't think this is normally supposed to vary, especially since this CPU does not have SpeedStep technology to lower the clock on battery power. And, the system is only used with AC (battery wouldn't hold a charge so I removed it to save weight).

Even so, I have set WinXP power profile to "Always On" which is supposed to keep a Speed Step processor from down stepping. Additionally, within NHC I set CPU Speed to "Max Performance". I don't know how else to "force" the CPU to run always at 3.2GHZ (I couldn't find any registry settings - anybody know of any?).

So, with no hardware or software changes to my system, I recently began noticing the following symptoms:

- Num & Cap Lock flash in Unison almost constantly (CPU hot indicator?)
- CPU temperature is 58C~60C
- As displayed in NHC, CPU Clock speed varies between ~1.1GHZ to 3.2GHZ

Could this be a power circuity issue? Any additional ideas?

Thanks for the input. I like the idea of a fresh build and will try that when I have some time.

I agree that 60C doesn't seem hot, however, I understood that the Num and Cap Lock LEDs flashing does indicate that the CPU is running hot. While 60C temps is not new behavior for my system, the flashing is. In fact, earlier the LEDs started flashing with the CPU temp at 48C!! Then later, with the temp at 58C they weren't flashing. Then, with the temp at 54C, they were flashing again. Then, at 56C they were not flashing, now at 56C they are flashing! So, I have no idea if this flashing is related to the CPU temp or not. However, the flashing LEDs also coincide with the fans switching to high speed, which would seem to indicate that the CPU is needing cooling. Am I wrong about the meaning of these two LEDs flashing in unison?

If temperatue was an issue, it shouldn't be now because the heat sink and fans have been cleaned, and new Arctic Sliver Ceramique, applied. Additionally, per the Arctic Silver instructions, the original thermal pad on the heat sink was removed (the problem was occurring before the pad was removed and new compound applied). The latter, combined with the behavior exhibiting at 48C leads me to believe that something else is going on. Any ideas?

Aside from the temp issue, I believe you answered my other questions in that, I did not know if the CPU was able to throttle itself. From your post, it appears that it does, which is actually what I would have expected. I understand now that the variance in clock speed is normal.

So, the only mystery left is why the num lock and caps lock LEDs periodically begin flashing.

Thanks again for all your input.

Good idea, I'll try to leave it in the BIOS overnight. As far as BIOS, no there's nothing that I'm familiar with.

I do see that the fan speed does coincide with the LEDs flashing, so I'm pretty sure it "thinks" the CPU is hot, even if the software indicates the temperature is not critical. Also, when the fans ramp up and the LEDs flash, the exhaust is "warm", however, that also is not abnormal (except for the flashing LEDs).