Dell XPS 9700 4k vs 1080p video playback power consumption

Light-Yagami · December 28, 2020

Hello,

Ever since I bought my XPS 9700, I wondered how much power difference does it make to just run the screen at 1080p, instead of 4k.

Most very smart people on numerous forums who haven't used the laptop will gladly tell you that it doesn't make any difference because you're effectively illuminating the same number of pixels, even though you're just rendering out 25% of them, duplicating the remaining 75%.- meaning the panels itself consumes so much more than the GPU does, that it wouldn't even make a difference, regardless of the resolution used.

These are my findings:

I tested power consumption with HWinfo64 and by playing an x265 file in vlc player. i7-10875H had 4 cores disabled, as well as turbo-boost, so that CPU consumption would be as low as possible, allowing me to see the difference only based on GPU power. Screen was at minimum brightness and windows power saver was used.

Average System power over 10 minutes (4K, full screen playback): 13.6W

Average System power over 10 minutes (1080p, full screen playback): 9.6W

A power reduction of 4W over 6 hours of video playback means 24Wh saved, adding more than 2.5 hours of additional uptime. This is a big enough difference that changing the resolution down to 1080p makes it worthwhile.

Furthermore, idle power consumption drops from around 9.5W to below 7W, which is huge! That means that at low brightness levels, XPS 9700 models with 4k screens can compare with native 1080p models. At higher brightness levels, 4k panels consumes more than 1080p panel, up to 3 times more. But I'm not comparing that here.

Conclusion: It does matter what resolution you're running at, and HD630 graphics does consume significantly more at 4K..

I hope someone finds this information useful.

Cheers