Any way to completely switch off the GPU when not needed?

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gamebox
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Any way to completely switch off the GPU when not needed?

Post by gamebox » Thu Oct 02, 2014 3:06 am

Hello folks. :)

I was wondering is it possible to switch the graphic card (and the GPU on it) in a computer completely off while the rest of the system continues running, in order to save energy when display output is not needed for prolonged time? For instance, if I leave the computer doing something for hours while I'm being absent, I wish to have my graphic adapter turn completely off (no power used and no heat emitted). I searched the BIOS but found only an option that seems to be the way GPU signals the monitor to switch itself off (V/H blank or something like that). I tried also using the power management options in a system related to display output, but although the monitor turned black and went to standby the GPU was still running (emitting heat as usual). I'm on Windows XP.

Thanks in advance!

Pappnaas
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Re: Any way to completely switch off the GPU when not needed

Post by Pappnaas » Thu Oct 02, 2014 4:58 am

If your talking about a desktop pc, then the answer is no. There is no mechanism to switch off PCIe cards implemented. Most newer cards will power down to really low consumption when the monitor is going into power save. When using multiple monitors, some cards will not cut the power down as low as when used with a single monitor.

If your talking about a laptop, then it depends on the hardware, most current Nvidia GPUs are being switched off as long as no GPU task is used, integrated Intel GPU takes over. AMD mobile GPUs are doing roughly the same.

gamebox
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Re: Any way to completely switch off the GPU when not needed

Post by gamebox » Thu Oct 02, 2014 12:45 pm

Yes, it's a desktop system. I thought it might be so, as there are many unoptimized tasks and pieces of hardware in a typical system and power efficiency is a recent "trend". The GPU in question is Radeon 4350 (yes, I know it's already one of the lowest power consuming cards :) ).

Another thing I noticed - it seems audio codecs (decoders actually) process audio streams in realtime when video is played regardless whether the sound output in a player is muted or not. I might be wrong, though - tried to come to conclusions only by monitoring CPU load. If it is correct, it is yet another wasting routine (albeit not of paramount importance given today's fast processors)...

edh
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Re: Any way to completely switch off the GPU when not needed

Post by edh » Fri Oct 03, 2014 2:48 am

There is ATI Dynamic Switchable Graphics:
http://www.anandtech.com/show/4839/mobi ... chnology/2

YMMV.

Another things is do you mean switching off the graphics card or the GPU? The two aren't the same. With the dynamic switchable graphics you will switch off the GPU but not the whole card as a small current is needed to get the PCI-E connection alive. Switching off the graphics card is only going to happen with PCI-E hotswap and that's not going to work on a desktop system.
it seems audio codecs (decoders actually) process audio streams in realtime when video is played regardless whether the sound output in a player is muted or not. I might be wrong, though - tried to come to conclusions only by monitoring CPU load. If it is correct, it is yet another wasting routine
That would probably be correct. I'm guessing your application involves transcoding video? Is it that you want only the video transcoded and are ignoring sound? There might be another route for doing this that avoids the problem like by doing it on the command line.

Pappnaas
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Re: Any way to completely switch off the GPU when not needed

Post by Pappnaas » Fri Oct 03, 2014 4:38 am

Your ATI 4350 is from 2009.

Back then the idle power consumption was guessed around 10-12W

viewtopic.php?t=51914

Given that any modern Intel CPU beats your card using the integrated GPU in benchmarks, i highly doubt that the back-then lowest idle consumption would hold against a modern system using integrated GPU.

And for your audio processing, while true in theory, i think when using a modern CPU, you are hardly able to measure the additional power used when processing "unecessary" audio data. Moreover, we have an architectural problem, because afaik no OS will tell the encoding process not to bother with audio data because the speakers are muted.

If you try and see the big picture, how much resources would be needed to change that behaviour at how much energy cost compared to the little bit of power that could potentially be saved?

That's a little like buying a new system spending 500$ to save 5 w/h. Yes, you save, but at what cost?

gamebox
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Re: Any way to completely switch off the GPU when not needed

Post by gamebox » Fri Oct 03, 2014 2:16 pm

@edh: I meant to "switch off" the graphic card/gpu the same way you would spin down a hard drive when data is not accessed for a while. After, say, 2 hours without any mouse movement or keyboard input, I wish the graphic adapter to stop processing/preparing the image and supplying it to the monitor. I would like it to switch all "switchable" internal components off (GPU, memory chips, whatever), and stop draining the power in a system and creating unnecessary heat as much as possible.

When talking about audio I didn't have transcoding tasks in mind. I thought about playing the video, in media player of sort. It seems pointless if audio is being decoded while sound output is muted in a player. The modern PC is fast enough and sound data is "packets" based, so starting the decoding/playback process again when sound is unmuted shouldn't be an issue.


@Pappnaas: Yes, my GPU isn't new. But it is one of the very good (efficiency) performers even in today's terms. I found this site (http://www.behardware.com/art/imprimer/781/) which measured it's power consumption at 7.7W idle-2D and 9.9W decoding HD H264 Video. Those would be all the power modes it will be using in my computer anyway.

My PC is Full-HD capable unit although very low-end, as I tend to reuse as many old components as possible. It has it's strongpoints
-67W TDP CnQ enabled Athlon 64 3500+, one of the faster single-core CPUs (sadly, I can't go for 45W AM2 A64 models at the moment)
-Sapphire Radeon 4350 (H264 decoder keeping the CPU in lower-power states as often as possible. I would have selected some later series as I wish to have XVID videos GPU decoded too, but the rest of the system imposed the limit below Radeon 5000 series)
-Corsair XMS 2x1GB DDR400 ram, CAS Latency 2 and dual channel
-Samsung 22inch Full-HD LED DVI monitor consuming about 16.8W at my settings
and weakpoints
-nForce4 chipset - the spaceheater! (chosen for compatibility reasons as I have 3 IDE optical units plus an IDE hard-drive)
-WinFast-Foxconn mobo (not the most respected brand, but good for as long as it is usable (3+ years in my setup and counting, bought secondhand)
-Rexpower PSU 350W reused from an old Duron1200 SDRAM machine, now requiring overhaul after about 8.5 years of (often heavy) use (occasional whines on load present today, probably because of semi-dry condensers which I plan to replace myself).
The computer is good as-is and I plan to keep it for a while as it gives quite a reasonable economy and decent everyday performance for it's low price. Any substantial upgrade would require significant investment (in new ram chips, new (and very expensive) PSU, compatibility add-on card for IDE devices or (worse yet) new optical devices and a hard drive which are mostly out of the question, etc etc.).

edh
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Re: Any way to completely switch off the GPU when not needed

Post by edh » Sun Oct 05, 2014 10:45 am

gamebox wrote:I meant to "switch off" the graphic card/gpu the same way you would spin down a hard drive when data is not accessed for a while. After, say, 2 hours without any mouse movement or keyboard input, I wish the graphic adapter to stop processing/preparing the image and supplying it to the monitor. I would like it to switch all "switchable" internal components off (GPU, memory chips, whatever), and stop draining the power in a system and creating unnecessary heat as much as possible.
So long as power management is enabled for the display then the graphics driver will follow suit. If you use a screen saver disable it and just set up DPMS instead. Graphics card power management normally extends to clocking down or switching off parts of the card (such as the GPU) but what happens is determined by the driver and how the video BIOS has been configured.

You could look at your video cards BIOS in RaBiT and see if you can make changes to the lower power state but that is more of an expert thing and risky in that you could make the card non-bootable if you don't fully understand the changes that you make.

What is your computer doing all of this time when it is left on?

I'll also say it again: A GPU is not the same as a graphics card. A GPU is a component on your graphics card, not the entire thing. Power management and switching one or the other off is very different.

gamebox
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Re: Any way to completely switch off the GPU when not needed

Post by gamebox » Mon Oct 06, 2014 7:19 pm

Thanks edh, I will try to mess with those DPMS related settings in BIOS as soon as I catch time.

The computer is often left on to finish some task - either to download something big or to finish a lengthy CPU-intensive task like video-transcoding or image/data compression. It happens often during the night, or my absence from home for a few hours (like going to work).

edh
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Re: Any way to completely switch off the GPU when not needed

Post by edh » Tue Oct 07, 2014 12:07 am

gamebox wrote:Thanks edh, I will try to mess with those DPMS related settings in BIOS as soon as I catch time.
You shouldn't need to in the BIOS. It should all be possible in your OS to enable display power management, you quite probably already have it enabled.
gamebox wrote:The computer is often left on to finish some task - either to download something big or to finish a lengthy CPU-intensive task like video-transcoding or image/data compression. It happens often during the night, or my absence from home for a few hours (like going to work).
Do you set your computer to shutdown when it finishes or do you have hibernate set up once the computer is idle. This might be worth looking at as it will save a lot of power.

gamebox
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Re: Any way to completely switch off the GPU when not needed

Post by gamebox » Tue Oct 07, 2014 5:35 am

The display power management options in a system (XP) didn't help with the graphic adapter. I set it to switch off after a minute just to try, the display went on standby as it was not receiving image data, but even after 10 or so minutes I didn't notice any perceivable temperature drop on the graphic-card's cooler. Therefore I wondered if the option only served to signal the monitor to go on standby (which in CRT era was a good thing to do).

I don't do hibernate, my 80 gig, slow, always very full, Maxtor doesn't like it (me neither). :) The system is shut down automatically by software, usually based on internet traffic, CPU load, or given time. If I happen to need to follow certain parameters of the task during my absence, the desktop "snapshot" utilities can be set to log everything. :)

Pappnaas
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Re: Any way to completely switch off the GPU when not needed

Post by Pappnaas » Tue Oct 07, 2014 6:16 am

I hope you are well aware that running XP is a risk nowadays?

Might be time to turn to Win7, which has also a better power management. If your system can't run W7 at decent speed, it might be time to move to a new PC.

gamebox
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Re: Any way to completely switch off the GPU when not needed

Post by gamebox » Tue Oct 07, 2014 6:31 am

Pappnaas, I've only recently upgraded to XP from Win98, in 2007 or so! :)

Yes, it is risky, but I tend to use the computer as a workstation with only temporary storage role. Everything "keepable" is on backups, so even a crashed system or a hard drive wouldn't mean great loss of data for me, just a temporary issue to get the system running again.

Pappnaas
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Re: Any way to completely switch off the GPU when not needed

Post by Pappnaas » Tue Oct 07, 2014 7:27 am

I got your point :D

But I'm not talking about hardware, it's just the fact that dozens of security risks are not being patched atm in XP, so as long as you connect to the internet, some malicious software could sent destructive mails from your account and you'd have a hard time protecting yourself against those kind of attacks, because they could bypass all your AV because of a vulnerability not patched.

gamebox
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Re: Any way to completely switch off the GPU when not needed

Post by gamebox » Wed Oct 08, 2014 7:41 am

I know. It's the risk I've been taking for quite a long time, though. I was always hoping that, in time, my system would get so old and so rare that hackers would simply stop wasting time creating threats for few quirks like myself. :) Now seriously, I only tend to move to another system when I can't use some important program/device anymore, or have other important issues.

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