Friday, May 15, 2009
Confused about EIST/SpeedStep
Intel SpeedStep is a technology that allows the processor to be underclocked when it's not busy. AMD has a similar concept called cool'n'quiet. The idea is that if the processor is slowed, it'll run cooler and use less power. If it's emitting less heat, then the building needs less air conditioning, and everyone is happy.
We've got a bunch of Dell OptiPlex 745, 755, and 760 computers at work. These machines all have Core 2 Duo or Pentium D processors that support Intel SpeedStep, and we're mostly running Windows XP SP3, which has support for speedstep in the OS. We also have a lot of users who like to use Remote Desktop from home (over the VPN), and so they leave their computers on all the time. This isn't necessarily a good use of electricity, so I wanted to be as conservative with power usage as possible. SpeedStep seems to be exactly what you'd want in this sort of situation.
We've enabled speedstep in the BIOS, we've set the power settings to 'minimal power management' which is supposed to turn on speedstep support in the OS. I've been able to verify that speedstep is running by checking the reported clock speed in the properties panel for "My Computer". But is it really doing anything?
So - one of the best ways to measure actual power utilization is with a Kill a Watt power meter, which measures how much power the machine is drawing from the wall. If you let stuff run over time, it'll also measure kilowatt-hours.
I fired up a OptiPlex 755 with all the power management stuff turned on, and let it run over a weekend. The power utilization was around 55 watt-hours as measures over a 70-hour period. I then turned off speedstep in the bios by setting it to 'home/office desktop', which is supposed to not underclock when on AC power. I verified that the CPU was running at full speed in the "My Computer" properties display. I let the machine run for a couple days and measured power consumption of... wait for it... 55 watt-hours.
What's up? Is speedstep a joke? Alternatively, is something along the lines of speedstep running all the time? The machine was idle under both scenarios. If anyone has any insight into this, please comment!
We've got a bunch of Dell OptiPlex 745, 755, and 760 computers at work. These machines all have Core 2 Duo or Pentium D processors that support Intel SpeedStep, and we're mostly running Windows XP SP3, which has support for speedstep in the OS. We also have a lot of users who like to use Remote Desktop from home (over the VPN), and so they leave their computers on all the time. This isn't necessarily a good use of electricity, so I wanted to be as conservative with power usage as possible. SpeedStep seems to be exactly what you'd want in this sort of situation.
We've enabled speedstep in the BIOS, we've set the power settings to 'minimal power management' which is supposed to turn on speedstep support in the OS. I've been able to verify that speedstep is running by checking the reported clock speed in the properties panel for "My Computer". But is it really doing anything?
So - one of the best ways to measure actual power utilization is with a Kill a Watt power meter, which measures how much power the machine is drawing from the wall. If you let stuff run over time, it'll also measure kilowatt-hours.
I fired up a OptiPlex 755 with all the power management stuff turned on, and let it run over a weekend. The power utilization was around 55 watt-hours as measures over a 70-hour period. I then turned off speedstep in the bios by setting it to 'home/office desktop', which is supposed to not underclock when on AC power. I verified that the CPU was running at full speed in the "My Computer" properties display. I let the machine run for a couple days and measured power consumption of... wait for it... 55 watt-hours.
What's up? Is speedstep a joke? Alternatively, is something along the lines of speedstep running all the time? The machine was idle under both scenarios. If anyone has any insight into this, please comment!
Labels: speedstep dell optiplex
¶ 2:55 PM
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I don't know if you read comments for your older blogs, but here is my opinion about your EIST (Enhanced Intel Speed Step) blog entry:
To check your processors speed - the "My Computer" properties display isn't the best thing since it usually shows the MHz the processor has while booting up.
The check your actual speed (and some other useful infos about your system) you could use CPU-Z. That's a little freeware program that you don't even need to install. You can get it here:
http://www.cpuid.com/cpuz.php
On the left side you can download the setup or just the ZIP file.
The main window of CPU-Z displays information about your processor and it's current speed AND voltage setting.
An OptiPlex 755 should have a Core 2 Duo E6600 processor running at 2400 MHz. (Just guessing - maybe it's a different type)
If EIST is active it should run at around 1600 MHz. If EIST is not active or your current cpu load is above average it should display 2400 MHz.
To disable EIST you should Disable it in the BIOS - AND - in your windows power management. (Set the power state to ALWAYS ON)
Then check with CPU-Z if the processor runs at full speed.
To enable EIST do the opposite. Enable EIST in BIOS and set windows power management to "Portable / Laptop"
Here some infos about XP and it's power management:
http://www.orthogonalthought.com/blog/index.php/2007/09/intel-speedstep-windows-xp-and-confusing-power-profiles/
Oh - and check that the other settings are the same (harddisk standby, system standby / hibernate and so on)
Then you SHOULD get different results.
EIST clocks the processor down AND reduces its voltage when in idle state or low load state.
Be aware that the difference will be kind of small. That's because all modern processors and operation systems can put the processor in a HALT state. (Has nothing to do with EIST). Early operation systems (Windows 3.x/9x/ME) and processors ran with empty calculation loops while idleing - so the processor was kind of always at full load. But since Windows 2000 and I think Pentium processors the system can send the processor a HALT command to stop executing. That reduced a lot of power consumation and heat dissipation.
But the power consumation difference between EIST and NO EIST should be measurable.
Excuse my bad english but I am from Austria (in the middle of europe)
Greetings
Niki
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To check your processors speed - the "My Computer" properties display isn't the best thing since it usually shows the MHz the processor has while booting up.
The check your actual speed (and some other useful infos about your system) you could use CPU-Z. That's a little freeware program that you don't even need to install. You can get it here:
http://www.cpuid.com/cpuz.php
On the left side you can download the setup or just the ZIP file.
The main window of CPU-Z displays information about your processor and it's current speed AND voltage setting.
An OptiPlex 755 should have a Core 2 Duo E6600 processor running at 2400 MHz. (Just guessing - maybe it's a different type)
If EIST is active it should run at around 1600 MHz. If EIST is not active or your current cpu load is above average it should display 2400 MHz.
To disable EIST you should Disable it in the BIOS - AND - in your windows power management. (Set the power state to ALWAYS ON)
Then check with CPU-Z if the processor runs at full speed.
To enable EIST do the opposite. Enable EIST in BIOS and set windows power management to "Portable / Laptop"
Here some infos about XP and it's power management:
http://www.orthogonalthought.com/blog/index.php/2007/09/intel-speedstep-windows-xp-and-confusing-power-profiles/
Oh - and check that the other settings are the same (harddisk standby, system standby / hibernate and so on)
Then you SHOULD get different results.
EIST clocks the processor down AND reduces its voltage when in idle state or low load state.
Be aware that the difference will be kind of small. That's because all modern processors and operation systems can put the processor in a HALT state. (Has nothing to do with EIST). Early operation systems (Windows 3.x/9x/ME) and processors ran with empty calculation loops while idleing - so the processor was kind of always at full load. But since Windows 2000 and I think Pentium processors the system can send the processor a HALT command to stop executing. That reduced a lot of power consumation and heat dissipation.
But the power consumation difference between EIST and NO EIST should be measurable.
Excuse my bad english but I am from Austria (in the middle of europe)
Greetings
Niki
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: 10:54 AM
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