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Monitor response time testing is a new addition to our reviews, where we use the Open Source Response Time Tool (OSRTT), developed by TechTeamGB. This measures grey-to-grey response times and presents the results in a series of heatmaps, the style of which you may be familiar with from other reviews.
Initial Response Time is the time taken for the panel to transition from one colour to another, where lower values are better. We present the initial response time, so overshoot is not taken into account and is measured separately. We use a fixed RGB 5 tolerance for each transition.
Overshoot is the term given for when a monitor's transition exceeds or goes beyond its target value. So if a monitor was meant to transition from RGB 0 to RGB 55, but it hits RGB 60 before settling back down at RGB 55, that is overshoot. This is presented as RGB values in the heatmaps – i.e. how many RGB values past the intended target were measured.
Visual Response Rating is a metric designed to ‘score' a panel's visual performance, incorporating both response times and overdrive. Fast response times with little to no overshoot will score well, while slow response times or those with significant overshoot will score poorly.
We test the AG405UXC at 144Hz, using all four of the overdrive settings found within the OSD.
We've skipped ahead to the Medium overdrive setting, as both the ‘off' and Weak options are simply not worth using due to the very slow response times on offer. Even using the Medium setting, we're looking at very poor results here, with an average GtG of 14.77ms. There's no overshoot, but the response times are very slow.
The most aggressive overdrive mode is the Strong setting, and even that is pretty weak by modern standards. We see an average GtG of 9.16ms, and some particularly poor fall times as shown in the left-hand side of the heatmap. There's still very little overshoot too, with just a couple of transitions showing errors greater than 10 RGB values, so I really think AOC could have cranked the overdrive much further than they did to improve response times. I don't think it would have made the AG405UXC a world-beater, but the current overdrive settings do not appear to be well optimised at all.
That's illustrated by the above pursuit camera images, using the Blur Busters UFO test. You can see the amount of visible trailing even using the Strong overdrive setting, while there's just a hint of a pale corona due to the small amount of overshoot.
You can really see the difference when comparing to a much faster screen, like AOC's own Q24G2A.
Looking at the best result in comparison to a couple dozen other monitors we've tested, the AG405UXC is one of the slowest we've tested. It's only faster than the Cooler Master GM32-FQ, putting it right towards the bottom of our chart.
