Graphics card power consumption (2D vs 3D)

[foustapfe]

Hi, I'm wondering if there is any noticeable difference in power consumption of the graphics card when the computer is idle between using compiz or kwin. My PC is always on and when I go to sleep I switch back to kwin. In that scenario, am I saving watts with that switch or not really? Is there really a 2D and 3D mode for graphics card? I haven't noticed a big difference in temperature while leaving the PC idle with compiz or kwin (one degree only). Card is a 8600GT.

Thanks.

[Radon]

There is very little difference for idle compiz and kwin because the graphics card doesn't have to do any calculations for the effects. There is still some slight usage (otherwise you could turn off the fan and not have to worry about the chip burning up ;) ) and the RAMDAC's are doing their thing.

I guess you can change your power saving settings to power off the screen when idle to save more power. In KDE it's: Control Centre > Peripherals > Display > Power Control.


I recommend the latest NVClock (http://www.linuxhardware.org/nvclock/) if you want to measure the temperature of the GPU and change the speed of the fan, as well as overclocking.

For temperature:
nvclock -T
To control the fan speed (change # to any figure you like, I use 30 for G92 GTS):
nvclock -f -F #

[maciekwpl]

and what does "#" mean here? Is speed calculated by the percentage of maximum speed of fan here? So if "#" is 100, it will work in the most efficient (and loudest ;)) way?

[Radon]

and what does "#" mean here? Is speed calculated by the percentage of maximum speed of fan here? So if "#" is 100, it will work in the most efficient (and loudest ;)) way?
Yes, just change the # to 10-100 in steps of 10.

[SmSpillaz]

For those of you who are using intel, I find that the graphics hardware does consume quite a lot of power because of all the wakeups it causes. When 3D is active, you'll get about 120~ wakeups per second in PowerTop due to all the vBlanking it does.

The vBlanking issue is set to be solved in the future, but for now we have to deal with it.

[grandrew]

So does that mean that using 3D desktop on intel based laptops will cause huge battery lifetime drop even while idling?