'Grid' issue

[pantalaimon]

The monitor is a Benq XL2420T.

When I use Lightboost there is an area at the top left of the panel approx 28cm wide and 5 cm in height. This area has a very noticeable grid pattern. It seems to me this is the grid of individual pixels, which is normally unnoticeable but is for some reason visible in this particular area.

I could try to take a photo of it later if necessary.

Any ideas why this might be?

I am getting rather tired of these monitors because I am on the third monitor, having RMA'd two already for major defects. This grid thing is the least severe so far, but still quite irritating.

[Chief Blur Buster]

Short Answer:
This is another normal artifact of many LightBoost monitors, but this one actually varies a lot from monitor to monitor. Some LightBoost monitors, manage to eliminate this artifact. This artifact is the most common on 24" 1ms panels manufactured 2013-2014.

Long Answer:
This is actually an interaction between strobing and LCD inversion (a temporal method of LCD panels to keep DC voltages balanced), that ends up creating this pattern. For more information about the purpose of LCD inversion in keeping a panel electrically balanced, see http://www.testufo.com/inversion and follow the links at the top (Lagom and Techmind) for the scientific explanations. The motion test itself will look quite weird (purples and greens will show up; this is normal and happens on almost all LCDs using the common tall-checkerboard inversion pattern.). There is a panel lottery factor that increases/decreases the intensity of this otherwise common LightBoost artifact. If this artifact bothers you, you may wish to upgrade to a newer monitor later this year.

Newer strobe backlights are improving, and panels are improving. LightBoost was the first strobe backlight that really did a super-good job of reproducing CRT motion clarity on an LCD desktop monitor, and is quite bleeding edge; it pushes the limitations of many LCD panels.