Lenovo ThinkPad X13 Gen 4: OLED screen profits a lot from dark mode

In the past, laptop buyers had the choice between TN and IPS - which was a huge quality difference, but both were based on the same LCD technology. Today, TN screens have been relegated to the trash pile of history - where they belong. The duality of choice however still exists on the laptop market. Buyers today often get the choice between IPS and OLED.

Different from TN and IPS, OLED is not an LCD variation. OLED is based on organic light-emitting pixels, which make a CCFL or LED backlight that LCDs need unnecessary. This fundamental difference has huge implications for all aspects of the screen, and of course that includes power consumption.

Since there is no backlight, OLED screens can show pure black by simply turning off the pixels. LCD panels in comparison can only display a very dark grey in place of black, as the backlight can not be fully turned off. By turning off the pixels, OLED saves a lot of energy when displaying black. This has a flip side: To display white, all sub-pixels of an OLED screen have to run at max capacity. Accordingly, power consumption when displaying white is far higher for an OLED screen. OLED screen power consumption is thus dependent on the displayed content: A mostly white website will drive up power consumption of an OLED panel, while a mostly black console will do the opposite. For the IPS LCD panel, the displayed content makes no difference in terms of consumption; IPS will consume less energy than OLED with a bright picture and more with a dark one.

When we test the battery life of a laptop, we use an automated script that loads different websites - our WiFi test. Those websites are mostly white/bright. OLED screens accordingly are disadvantaged in our WiFi test, compared with LCDs. Traditionally, most websites were white/bright, though nowadays, dark versions of websites are often available; this is true for Notebookcheck as well. And web-browsers often have the ability to force dark-mode onto websites that do not offer it.

We used this function to do the max. brightness version of the WiFi test twice with the Lenovo ThinkPad X13 Gen 4 OLED. Once the regular test and a second time with dark mode. The result: With dark mode, the battery lasted 1.5 hours longer.

This is why if you buy a laptop with an OLED screen, always use dark mode everywhere. If you can not stand dark mode, get an IPS LCD laptop instead.