Question about standby mode for the monitor/video card

[JSSheridan]

I have Windows power management set my monitor in standby mode after 15 minutes. Does the instruction to go to standby go to the monitor, or does it tell the video card to stop sending a signal to the monitor and the monitor then respondes by entering standby mode? I suspect it is the second, since my monitor will enter standby when I shut the system off and it is no longer sending a signal.

The point I am trying to get too involves the video card's power consumption. When I leave the system on overnight, I want to know if the video card is idling, or if it is in a power-saving standby mode. Is there a standby or reduced-power mode for video cards when they are not being (heavily) used.

I know that mobile CPU's have a similar feature that reduce their power consumption, but power conservation is much more critical in mobile systems. However, I would still like to see this feature on desktop video cards. My video card is idling somewhere around 16 hours a day, then I'll spend a several hours on the internet, writing e-mail, or programming, all of which are not video intensive. I may use the full capabilites of the card 2-3 hours a day at most, while somedays I never do.

If a signifigant amout of power can saved with a reduced-power mode over idle mode, and if it can be implimented without much trouble, would this be a worthwhile feature to you? With power requirements for 3D graphics cards increasing, I think it would be a good idea to have a standby mode on graphics cards.

 

[Lord Evermore]

As far as I know the video card doesn't go into a "power saving" mode, however when it's not generating a display it will naturally use slightly less power due to not processing instructions beyond a "keep alive" sort of thing. And during 3D processing it uses much more power. I would expect that the amount of power being used is highly insignificant in a desktop system when in standby mode.

There are several different modes for "sleeping" for video. One is just "blanking" the monitor, which just means the video card sends nothing but a blank signal and the screen just displays entirely black. That's the most basic mode and doesn't save any power, but was good to prevent burn-in on those nasty old monitors.

"Standby" or "suspend" actually signals the monitor to go into power saving mode (by removing the video signals). Usually you can see this happening when the monitor blanks, and it'll usually be a darker black than for instance when you use the "Blank Screen" screensaver in Windows. The indicator light on most monitors also switches to either a lower brightness or a different color to indicate it's in suspend. This uses significantly less power than just blanking the screen, on the order of 1/4 to 1/30th of the power of full on mode. There are a few ways the monitor can be turned off. One disables only the horizontal sync signal from the video card, which cuts power only slightly but allows a very fast return to power-on. That's "standby". "Suspend" mode disables the vertical sync signal and can cut power down to 30watts (full power monitors use in excess of 100 to 130 watts). If both signals are suspended, the monitor goes into "off" mode, which can use as low as 3 watts. You can get the same thing by unplugging the VGA cable.

Your motherboard BIOS will have a setting in the power management section that specifies which type of signal to send when your computer goes to "sleep" if you let that happen. Otherwise, your operating system can send the signal, and most do that now. Or you can download programs that do it, but there's not much need for that. In Windows, it's under the "Screen Saver" tab on Display Properties, in the power management section. Windows sends the monitor into Suspend mode after whatever interval you specify I think, not into full Off mode (since that would mean a very long delay while the monitor turns back on).