So, got my shiny new kill-a-watt power consumption meter, and decided to see if there was any noticeable difference in power consumption between the four leading OSes - Linux (ubuntu), Vista, XP and OS X.
The first test was using a dell 600m laptop, triplebooting ubuntu, XP and linux. Specs are 1.2Ghz Celeron M (no speedstep), radeon mobility 9000, 1gb ram, 40gb 4200rpm HD. The screen was always kept at medium brightness and wifi power management was turned off (full power) regardless of OS or any other options.
Ubuntu w/ Compiz on - Idle 17w, Load 26w.
Ubuntu w/ Compiz off - Idle 15w, Load 24w.
S3 Standby took a solid 1W.
So just running compiz on its own sucks up a bit of juice. Unfortunately the laptop doesnt support Aero so I couldnt compare it to compiz.
Vista High Performance Idle 20W, Load 27W.
Vista Power Saver Idle 15W, Load 23W.
Standby <1W
For Vista, "power saver" means USB selective suspend is turned on, and the processor is throttled to 50% of maximum speed. Since this chip doesnt have speedstep, its basically done in software, so theres no savings on idle, but there is some on load. Turning on USB SS instantaneously cut the power down 5W on idle, regardless of the processor throttling. USB SS had no effect on load, but the CPU frequency obviously did. Since ubuntu has USB SS on by default, its pretty much the same between the two.
The S3 standby mode seemed to take less power in Vista than it did in ubuntu, with the reading shifting back and forth from 0W to 1W.
XP High Performance 15w idle, 27w load.
XP Power Saver 13w idle, 27w load.
There's no option for CPU throttling in XP, so both are the same on load. I'm pretty sure USB SS is just on by default. The diff between the two is the ati graphics power settings, something I didnt have an option for in Vista or Ubuntu due to the available drivers. Toggling it to optimize battery mode shaved a good 2w off the idle.
So basically, theres nothing intrinsically different between the OSes. What it seems to come down to more than anything else is hardware and driver support for power saving features such as the GPU power savers, speedstep, etc. Compiz hurts a bit in ubuntu, and its so unreliable with S3 suspend/resume that its really not the best choice for a laptop that has issues with sleep.
So on to the desktop. Vista vs. OS X (hackintosh). Hardware is a E6300 (1.86Ghz) C2D, 7900GS, 4GB RAM, 250GB HD.
OS X x86 123w Idle, 140w Load. 2w Standby
Vista x64 123w Idle, 140w Load. 2w Standby
The PC entirely shut down draws 2w.
First, I checked to see if the bios power saving options (C1E half, EIST speedstep) actually had any effect. None, in either OS, on standby or idle.
What about aero? Unlike compiz, turning on or off aero didnt seem to change the power consumption. If anything, turning aero off sucks more power as moving windows around etc hit the CPU harder, but I cant tell if the story would be any different on a laptop vs. this desktop.
USB selective suspend and PCI-E link state management didnt save any extra in vista.
Overclocking to 2.5ghz changed both to 135w idle, 157w load - a pretty significant difference.
So basically, all OSes have the same power consumption, its the hardware that counts, which of course, makes perfect sense. 😛
And if theres anything to take away from all of this, is that standby/sleep/suspend is your best friend. It literally uses as much power as when the PC is entirely shut down. In fact, even less when you consider the wasted time and power booting and rebooting. There is absolutely zero reason to reboot unless you're forced to because of an update. Both Vista and OS X snap back from a resume within seconds. Nothing is faster than just leaving the PC on all the time, but at 135w idle, assuming you actually use the PC a few hours a day, you're throwing away about $15 a month ($180) a year just to save a few seconds.
The first test was using a dell 600m laptop, triplebooting ubuntu, XP and linux. Specs are 1.2Ghz Celeron M (no speedstep), radeon mobility 9000, 1gb ram, 40gb 4200rpm HD. The screen was always kept at medium brightness and wifi power management was turned off (full power) regardless of OS or any other options.
Ubuntu w/ Compiz on - Idle 17w, Load 26w.
Ubuntu w/ Compiz off - Idle 15w, Load 24w.
S3 Standby took a solid 1W.
So just running compiz on its own sucks up a bit of juice. Unfortunately the laptop doesnt support Aero so I couldnt compare it to compiz.
Vista High Performance Idle 20W, Load 27W.
Vista Power Saver Idle 15W, Load 23W.
Standby <1W
For Vista, "power saver" means USB selective suspend is turned on, and the processor is throttled to 50% of maximum speed. Since this chip doesnt have speedstep, its basically done in software, so theres no savings on idle, but there is some on load. Turning on USB SS instantaneously cut the power down 5W on idle, regardless of the processor throttling. USB SS had no effect on load, but the CPU frequency obviously did. Since ubuntu has USB SS on by default, its pretty much the same between the two.
The S3 standby mode seemed to take less power in Vista than it did in ubuntu, with the reading shifting back and forth from 0W to 1W.
XP High Performance 15w idle, 27w load.
XP Power Saver 13w idle, 27w load.
There's no option for CPU throttling in XP, so both are the same on load. I'm pretty sure USB SS is just on by default. The diff between the two is the ati graphics power settings, something I didnt have an option for in Vista or Ubuntu due to the available drivers. Toggling it to optimize battery mode shaved a good 2w off the idle.
So basically, theres nothing intrinsically different between the OSes. What it seems to come down to more than anything else is hardware and driver support for power saving features such as the GPU power savers, speedstep, etc. Compiz hurts a bit in ubuntu, and its so unreliable with S3 suspend/resume that its really not the best choice for a laptop that has issues with sleep.
So on to the desktop. Vista vs. OS X (hackintosh). Hardware is a E6300 (1.86Ghz) C2D, 7900GS, 4GB RAM, 250GB HD.
OS X x86 123w Idle, 140w Load. 2w Standby
Vista x64 123w Idle, 140w Load. 2w Standby
The PC entirely shut down draws 2w.
First, I checked to see if the bios power saving options (C1E half, EIST speedstep) actually had any effect. None, in either OS, on standby or idle.
What about aero? Unlike compiz, turning on or off aero didnt seem to change the power consumption. If anything, turning aero off sucks more power as moving windows around etc hit the CPU harder, but I cant tell if the story would be any different on a laptop vs. this desktop.
USB selective suspend and PCI-E link state management didnt save any extra in vista.
Overclocking to 2.5ghz changed both to 135w idle, 157w load - a pretty significant difference.
So basically, all OSes have the same power consumption, its the hardware that counts, which of course, makes perfect sense. 😛
And if theres anything to take away from all of this, is that standby/sleep/suspend is your best friend. It literally uses as much power as when the PC is entirely shut down. In fact, even less when you consider the wasted time and power booting and rebooting. There is absolutely zero reason to reboot unless you're forced to because of an update. Both Vista and OS X snap back from a resume within seconds. Nothing is faster than just leaving the PC on all the time, but at 135w idle, assuming you actually use the PC a few hours a day, you're throwing away about $15 a month ($180) a year just to save a few seconds.
