I have a Lenovo Yoga 2 Pro which has a resolution of 3200 x 1800 which I run at 200% scaling.

I have just bought an Asus PB278Q which has a resolution of 2560 x 1440 which I run at 100% scaling, and which I want to use for development.

However, all content on the external display is blurry.

So I tried the option for setting one scaling of 100% for all displays and now the external display is sharp as it should be, but the internal display is obviously useless in desktop mode because everything is too small. I verified that the external display is being driven at the correct resolution via the monitor's own information option which says 2560 x 1440 at 60Hz (I was at least pleased that the Intel HD 4400 graphics were able to drive both displays at their proper resolution with 32-bit colour and at 60Hz). I have a fully updated version of Windows 8.1 Pro Update 1.

So my guess is that Windows is rendering my external display off-screen at 200% and then crunching it down to 100% via bitmap processing.

Is this how Microsoft have implemented per-display scaling? There is no way I can tolerate such blurriness on the external display especially as I intend to use it mainly for development so clarity of text is important.

I've posted to this forum in the hope there will be other people with a similar setup. Is anyone able to help resolve this or is it simply a bad implementation of per-display scaling?

Here are a couple of comparison screenshots of the external display showing File Explorer and Visual Studio 2013:

Mixed scaling - internal display at 200%, external display at 100%

One scaling at 100%