Symptom 2: in XTU, when iGPU is under load, it throttles hard from normal 1200mhz to ~480mhz In 1080p with center image (no scaling), GPU is only at 20% load and it’s smooth.Īll I can say is that intel used a bunch of monkeys to write the scaling algorithm. In 1080p with full screen scaling, GPU is still 75% and it lags. It confirms that it is indeed windows that’s causing the lag and not some third party software.įirst symptom: while in 4K native resolution, when under GPU load (eg repeatedly opening the start menu), GPU load spikes up to 75% with lag. In task manager, when repeatedly triggering UI animations such as opening the start menu, dwm.exe seems to be taking up all the iGPU while discrete Nvidia card does nothing. I used a few programs that monitor the iGPU activity. Update: might have found the culprit, yet to fix One curious observation: When in 1080p, if I open the intel HD graphics control panel and select 'Panel Fit' to 'Center image' (default was maintain aspect ratio), it will render the whole image in a small portion in the middle of the screen with the sides blank, however, the UI is smooth in this mode. Installing latest drivers from intel and nvidiaĭisabling dedicated nvidia gpu, in device manager or BIOS (some other laptops with the same gpu combo had problems with optimus, doesnt seem like its the problem here though) Installing graphics drivers from Lenovo website (those are ancient!) OK, I thought it just needed some graphics driver updates, did that, still laggy. Then I updated to windows 10 (yes i know it's 2021 already) for better app compatibility.įirst thing I noticed after the upgrade (with the drivers provided by win update) was that UI animations such as maximizing windows, task view, and start menu popup was dropping frames really badly, both in 4K resolution (as expected) and, surprisingly also laggy in 1080p (unlike win8.1). So I've used my Y50 with the 4k screen for about 6 years now, running win8.1 in 1080p.

Lenovo y50 display driver