Can I slow my 2378FVU down below 600MHz?

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darrenf · #1 Post by **darrenf** » Tue Sep 21, 2004 9:17 pm

On one occasion, I noticed my CPU running at 298MHz according to system properties, but I haven't been able to get the machine to do that again. 600MHz is the slowest it will go.

I would like the CPU to slow down as much as possible when idle to reduce head/battery usage. Can I change the lower threshold?

-darren

csv96 · #2 Post by **csv96** » Wed Sep 22, 2004 8:54 am

Try the "Super Power Saver" or "Maximum Battery Performance" profiles and it should slow down even more. My Pentium M 755 will speedstep down to 179mhz when in either of these modes on battery power.

darrenf · #3 Post by **darrenf** » Wed Sep 22, 2004 5:08 pm

Super power saver mode still yields 600MHz. Could the BIOS settings affect speeds under Windows XP? My XP install is a clean install rather than a pre-load, but I have all the drivers obviously related to power management and they are up to date.

Any other ideas?

-darren

csv96 · #4 Post by **csv96** » Wed Sep 22, 2004 6:30 pm

Are you using IBM's Battery Maximiser Wizard/Battery Gauge to select the profile or are you using Windows XP's power management screen to select the profile?

darrenf · #5 Post by **darrenf** » Wed Sep 22, 2004 8:32 pm

The IBM tools. My power consumption is higher than it used to be and I'm trying to track it down. It might just be because I upgraded from the T41 to a T42 with faster CPU/GPU, but I think the battery life was good in the first month that I had the T42 and only went downhill recently.

I've been able to clock the GPU down a lot, but I have very little control over the CPU. I like the adaptive CPU speed, but I think 600MHz is too high as a base speed.

What speeds are other people seeing? I have the 1.7GHz CPU.

-darren

whealey · #6 Post by **whealey** » Thu Sep 23, 2004 1:04 am

I have a 2.0Ghz cpu and i have only seen 2.0 ghz speed (1.99) actual, and 600mhz speed.

awolfe63 · #7 Post by **awolfe63** » Thu Sep 23, 2004 7:39 am

I don't think so.

See ftp://download.intel.com/design/mobile/ ... 218903.pdf pp. 20-21

Looks like the lowest speed on Dothans is 600MHz.
I have at one time or another seen all the listed speeds for my 735 - but no others.

darrenf · #8 Post by **darrenf** » Thu Sep 23, 2004 10:21 am

awolfe63,

Good find! Thanks for the research!

I'll give up now.

-darrenf

awolfe63 · #9 Post by **awolfe63** » Thu Sep 23, 2004 10:38 am

darrenf wrote:The IBM tools. My power consumption is higher than it used to be and I'm trying to track it down. It might just be because I upgraded from the T41 to a T42 with faster CPU/GPU, but I think the battery life was good in the first month that I had the T42 and only went downhill recently.

I've been able to clock the GPU down a lot, but I have very little control over the CPU. I like the adaptive CPU speed, but I think 600MHz is too high as a base speed.

What speeds are other people seeing? I have the 1.7GHz CPU.

-darren

Remember - the Dothan CPU's are adaptive even at a fixed speed.

Set your machine for max CPU (1.7GHz in my case). Sit at desktop for 10 minutes. Then run something at 100% for 10 minutes - sepecially something with floating point or mmx (game - photoshop - acrobat distiller). Watch power consumption and CPU temperature go way up. Mine can go from 18-19W to 35-40.

So at 600MHz - you still aren't really running that fast. In fact - you may not be running any more actual powered clock cycles at max speed - the difference is that at 600MHz the voltage is lowered. Even if you could slow the clock down more - you would not be able to lower the voltage any more so you may save no power.

darrenf · #10 Post by **darrenf** » Thu Sep 23, 2004 10:54 am

awolfe63,

Thanks again! I thought that the power saving in these chips was more sophisticated than SpeedStep, but then I saw that SpeedStep was still present, so I thought that maybe the hype about the Pentium-M power management was just that, hype. I'm glad to hear that it really does micro-manage power.

As much as I love MobileMeter, I wish there was a way to identify power usage by device (fan, HDD, backlight, CPU, GPU, etc).

I think my power drain is coming from the fan which seems to run more than on my T41. The culprit seems to be the ATI 9600. On my T41 the 7500 was not actively cooled and so the fan didn't activate unless the CPU needed cooling. This machine has the "long fan" which cools the GPU and seems to run a lot.

Fortunately, it's quiet as a mouse, so it doesn't irritate. I don't really know when it's running unless I put my ear up to the vent.

-darren

csv96 · #11 Post by **csv96** » Thu Sep 23, 2004 10:56 am

Found another page confirming the 600mhz speed:

http://www.intel.com/support/processors ... 007981.htm

But I swear I've seen my Pentium M 755 run at 179mhz and 299mhz on battery power.

darrenf · #12 Post by **darrenf** » Thu Sep 23, 2004 11:05 am

csv96,

And I swear I've seen mine rated just below 300 once too. I think it might be the testing mechanism. When I saw the 300 rating, it was in the My Computer properties window. Since I installed MobileMeter, it has never fallen below 600.

Perhaps MobileMeter polls the CPU for voltage level or clock speed where Windows measures it by timing code execution within a critical code segment. The latter might be effected by the Pent-M's "other" power management features (like the time required to wake up a subsystem).

Just a guess.

-darren

awolfe63 · #13 Post by **awolfe63** » Thu Sep 23, 2004 11:33 am

darrenf wrote:awolfe63,

Thanks again! I thought that the power saving in these chips was more sophisticated than SpeedStep, but then I saw that SpeedStep was still present, so I thought that maybe the hype about the Pentium-M power management was just that, hype. I'm glad to hear that it really does micro-manage power.

As much as I love MobileMeter, I wish there was a way to identify power usage by device (fan, HDD, backlight, CPU, GPU, etc).

-darren

I would love it too. Unfortunately it is not practical - the current monitoring devices are too expensive and to measure chips, the motherboard power planes would need to be isolated in complex ways that reduce reliability.

I actually became interested in this stuff back in my basic research days when I worked with Intel on the 486SL - one of their first low-power designs. For internal use they had developed a special motherboard that allowed us to measure the power to each component separately. It was very cool. In those days, for certain tipes of code like the windows idle loop, you could decrease power by adding NOP instructions and making the code slower! Now days, the chips are much smarter.

darrenf · #14 Post by **darrenf** » Thu Sep 23, 2004 11:09 pm

awolfe63,

Thanks for the very informed response.

I guess I'll just keep waiting for the next breakthrough battery technology.

I want my atomically powered laptop dangit!

-darren

Can I slow my 2378FVU down below 600MHz?

Can I slow my 2378FVU down below 600MHz?

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