The Xiaomi Mi 9 is the latest and greatest full-fledged flagship from the company, though it may have been overshadowed by the competition. The OnePlus 7 Pro is one such device, which has a DisplayMate award-winning display coming in at 1440p with a refresh rate of 90Hz. The added fluidity of a high refresh rate display instantly makes any device nicer to use, though there aren't many high refresh rate devices on the market. If you're willing to unlock the bootloader of your Xiaomi Mi 9, however, you can flash a modification which bumps up the display refresh rate to an astonishingly high 84Hz.

Warning: It's possible that this could damage your display. Proceed with caution.

Overclocking displays isn't exactly a new phenomenon, though it's nowhere near as popular as overclocking a CPU, GPU, or even RAM. For example, an older monitor of mine could only overclock from 60Hz to a bit over 70Hz. 60Hz to 84Hz is incredible, and if all Mi 9 displays are capable of it then it might be worth checking out. You need an unlocked bootloader, as you'll have to flash an image to the dtbo partition on your device. You can download both the image file required and the application to flash it in the linked thread below.

Xiaomi Mi 9 XDA Forums

To install the mod, download both the Lanthanum System Toolbox APK and the modified dtbo image file. Select partition settings from the hamburger menu of Lanthanum, select dtbo, and export the image. That will create a backup, which you can name and store on your device storage. Next, select dtbo, flash image and choose the modified dtbo image. All you need to do now is reboot.

I tested it on the latest Xiaomi.EU ROM and the difference after rebooting was immediately noticeable. People have run the mod for a few days without major issues, but some have noticed a slight green tint of the display, though it's not hugely noticeable and certainly doesn't look bad. The mod was originally created on the Xiaomi MIUI forums, and you can check out that original thread here.

Overclock the Xiaomi Mi 9 screen to 84Hz