Power Management: ATI Catalyst vs. Open-Source ATI Driver

[oblivious_maximus]

I was bit disappointed to find this article had absolutely nothing to do with power management - it should have been called "Power Consumption: ATI Catalyst vs. Open Source ATI Driver" IMHO.

Power management, in this case, is having your video card automatically use lower core/memory clock speeds (and whatever else can be done to save power without losing functionality) to save power when one is not using 3D and has no need for full power and full clock speeds.

I wanted to know how far along the power management support in the open drivers was. Does the card automatically clock down for 2D? And clock back up for 3D? Does it do this reliably, ie: doesn't stutter in 3D jumping back and forth between clock speeds? Does it stay at 2D clock speeds when using 2D or does it jump higher for some tasks(if so, is that noticeable?)? Does it share the same ridiculous limitation as fglrx (plug in a second display and PowerPlay ceases to clock down AT ALL)? How far does it clock down? Is it too far to keep a 2D desktop snappy? These are some of the things an article purporting to compare power management features between 2 drivers should be testing (and obviously what power savings can be had in the process). Not power consumption at idle and under load when no power management features are even enabled..

[BlackStar]

Why do the apps mess with clock speed to conserve power? You can't do it. The only way to really make a dent in power usage on a video card or a cpu is to lower voltage.

Indeed. The whole point of underclocking is to allow for lower voltage. Underclocking without undervolting is a waste of time (and power).

PS. I've got pure DC desktop system so if you can't achieve the same results as me it's because a capacitor in a power supply is never as voltage stable as 120lbs of lead acid batteries.

How does this setup work? Are you using a massive UPS to feed a high-efficiency DC-DC PSU (e.g. pico or similar)?

I was planning to use pico on my current system, but decided against it in the end - I do 3d graphics and I didn't want to be juice-limited. The pico is now recomissioned to a wireless router/server PC running on my rooftop.

Edit: sorry for derailing this thread, let's take this discussion to PMs.

[suokko]

For r500 fglrx stock settings aren't setting card to lower power state unless I unplugged the laptop so if test was done plugged into wall then fglrx test doesn't show anywhere near what real power consumption is in battery usage. (I noticed this problem when I asked why the stupid fan was keeping noise all the time.)

[Hephasteus]

Indeed. The whole point of underclocking is to allow for lower voltage. Underclocking without undervolting is a waste of time (and power).



How does this setup work? Are you using a massive UPS to feed a high-efficiency DC-DC PSU (e.g. pico or similar)?

I was planning to use pico on my current system, but decided against it in the end - I do 3d graphics and I didn't want to be juice-limited. The pico is now recomissioned to a wireless router/server PC running on my rooftop.

Edit: sorry for derailing this thread, let's take this discussion to PMs.

Not really derailing thread since we are discussing power usage. I'm using a pico 120 watt power supply with a soldered on extra connector for cpu power and a soldered on extra universal connector from an old sort of works if you pull enough amps neo he380 power supply. I can plug any of the cable management cables into the that plug and run my satas off it right now.

Pico goes to front panel switch which is "ignition" and then to back panel switch with is on/off then out back of case and I'm running 6 feet of 14 guage radio control car electric motor wire. It's getting a .5 volt drop along the whole run so i have to switch over to 10 or 8 guage. This goes to 2 duralast 110 amp hour 195 reserve capcity deep cycle batteries which get charged from solar panel I deploy out the deck or through a samlex BP series power factor correcting charger. Or both letting the solar panel drop the amount of power the charger supplies.
http://www.abra-electronics.com/prod...p-1-c-618.html

My 19" lcd uses about 44 watts but once I convert it to pure dc it will use around 32 watts as it isn't power factor corrected.

A 120 watt dc/dc power supply will do anything a 200 watt ac supply will do. The pico 250 watt supply will run huge systems if you just tweek them a bit and don't go nuts on crazy stuff. No need for 130 watt cpu which will pull about 90 watts on that supply and no need for SLI when one card works about as well. It will run any 65 watt rated cpu and any video card but the 4 or 5 most power hungry ones may need to be devoltaged and declocked just a tiny tad. If a video card needs 200 watts from an AC supply it will only need 160 watts from a dc supply and if it's devoltaged and declocked right you can get the super power hungry cards down to managable power usages.

You could probably run a quad sli system off of dc if you made up some pci-e 6 pin and 8 pin cables that would switch on straight to battery upon receiving power good signal from supply. The battery system wouldn't go outside the voltage regulation ranges that the cards use anyway as they have 4 or 6 phase regulation.
Such a system would be awesome if it was actually engineered entirely into the system. You could literally switch off cards with toggle switches if the bios and os were made aware that a card was either there or off.

But the system I did was because you can't power factor correct the computer entirely because the currents and voltages and everything fluctuate too much. The charger can maintain .96 to .98 power factor because it only runs a pulse width modulation, meaning it cycles on and runs it's full current for a pulse time and cycles off. The pulses affect the battery about .1 volts. The longer it stays on the more power it feeds but when it's on it's almost pure efficiency and the best you can ever hope for with an AC supply is .85. They simply are unable to give power the way the charger does. The power savings isn't large on my system but if you scaled it to a 2 panel 400 watt total folding rig or server you'd lose 120kw a month of usage. But the sad fact is if that people just saved 15 percent on power usage the strain on the grid would drop power generation needs another 10 percent as most grids don't use nearly enough copper to run themselves efficiently.

But the most important thing is once i'm done with my dc board for monitor my system will run through multi day power outages and a laptop won't do that.

[krogy]

You got me there I study mathematics, and I have a course in statistics and time series analysis behind me.

It is not possible to quantify the uncertainty, it have to be measured or know. Yes, you measure the uncertainty with equipment that you know is more precise than the one you want to know the uncertainty for

As for this test with power measurement, I don't how how they where measured or with what equipment, but without that information the test is useless, and it doesn't tell anything.

If this is not possible, as it sometimes is, you have to do more than 28 measurements for each point. Why 28, because then you are in the 95% confidence interval.

Which means that there is a 95% change that what you have measured is the right values.

100% is impossible. That formula doesn't allow this.


The Phononix test suite is worth nothing (sorry to say so) to anyone with an engineering background. The results doesn't tell a damn thing.

i joined the forums just to answer this :P

i would agree with you in general but in this particular case you're blowing it out of proportions. If you look at the plots, and consider that are made out of lots of data, they are as smooth as silk. The variance of the error is really, really small to the point that if there were error bars you wouldn't see them.
on the other hand, the eventual bias will act in the same way to the two set of measurements and thus can be disregarded.

but yeah, error bars would give more justice to the plots in general.
maybe you should contribute to the project and add them

[alec]

Test does not account for video cards that actually lower clock speeds and voltage with PowerPlay. As somebody compared, the X1950Pro doesn't, but 4850 does. Thus power consumption is nearly same on X1950, but a lot less idle consumption with fglrx on 4850.
And

Had we manually lowered the PowerPlay state, which reduces the frequencies that the GPU operates at along with its voltage, we would have certainly seen a lower power consumption, but at a lower frame-rate.

PowerPlay lowers clocks in idle without noticeable slowdown

[korpenkraxar]

From the article:

Had we manually lowered the PowerPlay state, which reduces the frequencies that the GPU operates at along with its voltage, we would have certainly seen a lower power consumption, but at a lower frame-rate.

Yeah that is most likely the case and I am pretty sure I know why you guys did not report anything on that. I installed the fglrx 9.2 driver on my Thinkpad Z61m with an X1400 graphics card running Arch Linux and tried:

aticonfig --set-powerstate=1

a few times. Instant and consistent crash each time! Seriously did you try changing the power state on that laptop and did it work?

[Noah]

From the article:



Yeah that is most likely the case and I am pretty sure I know why you guys did not report anything on that. I installed the fglrx 9.2 driver on my Thinkpad Z61m with an X1400 graphics card running Arch Linux and tried:

aticonfig --set-powerstate=1

a few times. Instant and consistent crash each time! Seriously did you try changing the power state on that laptop and did it work?

Hey Guys,

This article is really pointless, because it doesn't address power management. With aticonfig --set-powerstate=1 on my laptop I got a huge power saving, (around 7W) as measured in powertop and through battery life over the default settings you tested.

My laptop also ran much cooler and quieter.

(Laptop is hp nx8420 with X1600)