ePowerManagement + SpeedStep

This is to discuss the benefits and drawbacks of Acer's ePowerManagement utility. I own the TravelMate 4002 and so will be using that model as the reference in this enquiry.

Does ePowerManagement use the Pentium M's Enhanced SpeedStep technology? Basing it on performance monitors of the CPU frequency, I do not think so. (I have sent off an email to Acer to confirm, the response of which I will post.) This means that when you set the CPU speed in ePowerManagement to low (600MHz), it remains at that 600Mhz, regardless of what you are doing and what load the CPU has. Similarily, when you set the CPU speed in ePowerManagement to Maximum (e.g. 1600MHz), it stays at 1600MHz no matter if you are opening five programs at once or just word processing. Windows power management, on the other hand, uses the processor's SpeedStep technology, which allows the CPU to run at its lowest frequency (600MHz) under normal conditions and then automatically step up to higher frequencies (6 steps in total) to accomodate more intense CPU demands (e.g. opening five programs at once).

What does this mean for performance and battery life? Using ePowerManagement to set your CPU speed to low allows you to achieve the most life from your battery because it does not allow the CPU, under any circumstance, to raise above its lowest speed . This battery saving can also be achieved in Windows by usings the Max Battery scheme, which disables SpeedStep and forces the CPU speed to its lowest setting at all times - essentially the same as what ePowerManagement does. However, using the Portable/Laptop scheme in Windows allows SpeedStep to use the CPUs lowest setting under normal conditions and only raises it when it is needed, and thus is good on battery life but not as good as always limiting the CPU to its lowest speed as in the above two cases. As for performance, ePowerManagement always limits the performance to whatever CPU speed you select, where as Windows, using SpeedStep, allows the CPU speed to increase if it is required so performance is effectively never sacrificed, while still achieving low power consumption.

So what is the benefit of using ePowerManagement? The ability to turn off specific I/Os like the LAN, FireWire, and PC Card ports. That is about it.

The drawback of ePowerManagement is the limitation of performance from not allowing the processor to dynamically (and automatically) adjust the CPU speed as it is required. Also, in situations where you are chiefly concerned with performance (e.g. AC power) and have ePowerManagement set the CPU speed to Maximum, the CPU is constantly runnning at its highest frequency (e.g. 1600MHz), regardless of what you are doing. This causes the 'loud' fan to coming on every five minutes even when the machine is idling. I find this to be annoying and wasteful. SpeedStep corrects this by allowing maximum performance but only when you need it, thus keeping the CPU temp as low as possible.

For me, the choice is clear: I have uninstalled ePowerManagement and now happily enjoy performance, battery life, and (near) silence operations whether I am plugged in or mobile. Not to mention the satisfaction that I am liberating the CPU to use all the brains it was endowed with.

A little verbose, I know, but what are your thoughts?

/hobbs

 

While using mobile meter I noticed that when selecting the highperformance in epowermanagement windows reports the cpu as runing at full speed but mobile meter reports that speed step is enabled thus when runing a simple word doc it runs at the lowest speed but when entering a game it runs at full speed.
I am happy with e power management. It is nice that you can enable and disable devices when on batery to preserve power.

Acer Travel mate 4002Wlmi/1.6 dothan/512/60gb/970064mb/DVD-Dual/15,4wxga

 

I am not familiar with 'mobile meter' but I used the performance monitor that is built into Windows XP to show the current CPU frequency. You can access it by typing perfmon in the Run... console and following a few more steps. It shows the realtime frequency of the CPU. Using 'Maximum' in ePowerManagement showed the CPU running 1600MHz all the time where as using the Windows power management the frequency was bouncing from 600MHz to 1600MHz depending on what the computer was doing. Qualitatively, I noticed that 'Maximum' on ePowerManagement caused the 'loud' fan to run much more often then when using Windows power management.

As for being able to turn off certain ports, how much battery life could that possibly conserve, really? The circuit in those ports are only complete when a device is plugged into them anyway.

/hobbs

 

I think its just for TravelMate's.

 

Ok so can someone clarify whether this Acer ePowerManagement comes only on the TravelMates or does it come on all the Centrinos? Aspires and TravelMates alike? Coz I cant seem t find this thing on my aspire.

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Acer Aspire 1683WLMi
1.7 Centrino (Dothan, 2MB Cache), 512MB RAM, ATI Radeon 9700 Dedicated, 60GB, DVD-Dual(RW), 15.4" Wide Screen, Bluetooth, 3 in 1 Card Reader, 8 Cell Batt (4+ Hours).

 

WIndows and many athor programs report the cpu freq bad. EVEN WN USING CPU-Z sometimes it goes wild.
http://www.geocities.co.jp/SiliconValley-Oakland/8259/release/0310/mm0310.zip
Download mobile meter and you will what i am talking about.

Acer Travel mate 4002Wlmi/1.6 dothan/512/60gb/970064mb/DVD-Dual/15,4wxga

 

I installed the ePowerManagement and uninstalled it. I only use the eManager (eSetting and ePresentation) now. They do the basic things (adjust the LCD brightness) and then I use windows to the standby/hibernation/powermeters to the rest. IMO, ePowerManagement is pure crap.

*# Acer TravelMate 4001WLMi #*
Intel Pentium M 715 1.5Ghz 2MB Cache (Dothan)
512MB PC2700 DDR333
ATI Mobility Radeon 9700 (64MB)
15.4' WXGA wide (16:10) TFT
60GB Hitachi HDD
DVD-DUAL (DVD+-RW)
802.11b/g Wireless LAN

 

<blockquote id='quote'> quote:<hr height='1' noshade id='quote'>Originally posted by maia

 

If I'm using the battery and connect the AC power, the LCD brightness will go to 100%. If AC power goes out or I'm working with the battery, the LCD is set to be at 67%. Works for me...

*# Acer TravelMate 4001WLMi #*
Intel Pentium M 715 1.5Ghz 2MB Cache (Dothan)
512MB PC2700 DDR333
ATI Mobility Radeon 9700 (64MB)
15.4' WXGA wide (16:10) TFT
60GB Hitachi HDD
DVD-DUAL (DVD+-RW)
802.11b/g Wireless LAN

 

<blockquote id='quote'> quote:<hr height='1' noshade id='quote'>Originally posted by maia

 

i m using epowermanagment on my 1681wlci.
however, i found that when the CPUSpeed is set at High, the processor speed stay at 600Mhz and then shoot up to 666,800,1Ghz and 1.5Ghz according to usage.
Setting the speed to "medium", resulted the same start up speed at 600 and then shoot up to 1Ghz.
However, the other 2 extreme, Max and Low fixed the operating speed at 1.5Ghz and 600Mhz respectively for each option.
The operating speed is observed using MobMeter 0.3.1.0
http://dssc3031.ece.cmu.edu/~tamaru/mobilemeter/mobilemeterreadme-e.htm

However, my concern is that, will the speed throttling reduce the processors or RAM's life since both of them have to adjust themselves dynamically instead of operating at a prefix speed. Comparing this throttling with heat, which would reduce the life of the components?

 

Hey Xenothrix.. can u tell me if u installed the epowermanagement on the aspire 1680 tyourself or did it come with it, coz i cant seem to find it on mine? Is there a palce where i and download it form?

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Acer Aspire 1683WLMi
1.7 Centrino (Dothan, 2MB Cache), 512MB RAM, ATI Radeon 9700 Dedicated, 60GB, DVD-Dual(RW), 15.4" Wide Screen, Bluetooth, 3 in 1 Card Reader, 8 Cell Batt (4+ Hours).

 

Thanks for the reply xenothrix, this mobile meter is neat.

BTW, I still haven't received a email response from Acer about their ePowerManagement using SpeedStep.


Workhorse: TM4002WLMi