Power-hungry display — Dell XPS 13 4K UHD configurations have shorter battery life by several hours

[Redaktion]

If you're in the market for a new XPS 13 Ultrabook, you may want to consider the less expensive 1080p options for their significantly longer runtimes. We are able to measure a difference of 4 to 5 hours when running the same WiFi test on both the FHD and 4K UHD SKUs.

https://www.notebookcheck.net/Power-hungry-display-Dell-XPS-13-4K-UHD-configurations-have-shorter-battery-life-by-several-hours.414493.0.html

[Steven Chien]

Could you run a test using the standard loop on the 4K machine, but with the resolution dropped to downscaled 1080p?

I know the display should draw the same amount of power, but I wonder how much of the extra consumption actually comes from stress on the iGPU as opposed to the screen, which in theory should consume the same power considering it is emitting the same amount of light (heat notwithstanding).

I bought a 4K laptop and specifically run it at 1080p whenver on battery power, because the 4K options are usually brighter and have better color reproduction. I would love to know if I'm actually saving any battery life, or if its purely a placebo.

[sticky]

Dropping down the resolution DOES NOT SAVE BATTERY LIFE at all, because laptop is still powering the same number of pixels.

I'm more interested to see some tests on Full HD LPD (Low Power Display) on HP and Lenovo laptops.

[M2018]

"Dropping down the resolution DOES NOT SAVE BATTERY LIFE at all, because laptop is still powering the same number of pixels."

Your logic is "brilliant"!  ;D

[jeremy]

Dropping down the resolution DOES NOT SAVE BATTERY LIFE at all, because laptop is still powering the same number of pixels.[...]

There is a nontrivial amount saved from the Intel IGP. It's already a bit taxed at 1440p. At 4k, it's running at near full tilt just to keep up with desktop composition.

That being said, one would be way better off not getting the 4k display, especially on a 13" laptop. There comes a serious point of diminishing returns when it comes to DPI.

[DavidC1]

The iGPU doesn't get "taxed" running 4K video, seriously.

There are dedicated parts in Kabylake and later Intel chips to do hardware decoding, and it takes almost nothing of the GPU.

The iGPU on full 3D can take up 10W by itself. If it were stressed as you were saying, you'd be hard pressed to get 5 hours battery life with the screen off, nevermind a 4K screen. In fact, the CPU+iGPU combo takes less than 1W to run 4K content, again because its hardware accelerated.