Windows 10 dual monitor - lower res monitor is blurry

Solution 1:

This is the way DPI scaling works on Windows 10. The primary display is used as a reference, so it’s always sharp. On other displays, there are two possibilities:

• The application is “per-monitor” DPI aware – if correctly programmed, it will be sharp on all displays. It will use the DPI of the display where the majority of its window is located. Example: Firefox
• The application is “system” DPI aware – it will be sharp on your primary display. On other displays with different DPI, it will not be sharp, because Windows will resample the output image. Example: MS Office

There are of course also unaware applications. Unfortunately, there aren’t many “per-monitor” aware applications. There are also applications that have the “per-monitor” aware flag, but do not scale at all. Lync/Skype for Business is one such application.

You can use Process Explorer to check program’s awareness (the column is deselected by default):

It might be noteworthy that DPI scaling on OS X works exactly the same, except it uses a less blurry scaling algorithm.

tl;dr: Working OK, by design.

Solution 2:

If one monitor is running from a dedicated graphics card and another from the on-board graphics card, Windows treats the two monitors as a continuous desktop, but the different DPI settings have to be processed by the graphics controller the monitor is attached to. If this is the case for you, you might try applying the following steps to set a CUSTOM value of 100% rather than a "standard" value of 100% (don't ask me why this works, but it worked for me):

1. Set custom scaling to a value that isn't 100% (Windows won't let you set a custom value of 100% if you already have a "standard" value of 100% set).
2. Click apply, then re-login later.
3. Set the custom scaling back to 100% and click re-login later.
4. Restart the computer.
5. Don't mess with DPI settings afterwards.

If the issue is specific to certain programs, you can check "disable display scaling on high DPI settings" in the compatibility tab under properties for the affected programs.

If the issue is global (everything everywhere is blurry) I would play with different versions of the drivers for the graphics controller the HP is connected to. I would also strongly suggest calibrating your Cleartype settings after you've set the DPI settings.