I usually measure the response time of 120Hz monitors twice, at two different refresh rates. The GD245HQ called for a third test, with the response time compensation technology turned off, due to the defect I've described above.
At a refresh rate of 60 Hz the monitor’s average response time is 3.1 milliseconds (GtG).
The average RTC miss is 7.8% and the monitor takes 13.6 milliseconds to correct it.
At a refresh rate of 120 Hz the monitor's average response time is 3.0 milliseconds (GtG) whereas the errors become far less conspicuous: the average miss is 6.2% and the correction time is 5.5 milliseconds. These numbers are as good as those of other modern 3D monitors. For example, the ViewSonic VX2268wm has a lower response time but a higher level of RTC errors.
Thus, the doubling of the image in stereoscopic mode is just as conspicuous on the GD245HQ as on other 3D monitors such as the Samsung 2233RZ or the abovementioned ViewSonic. You can spot the characteristic artifacts if you know where to look for them, but they are not too gross and do not spoil the fun from 3D gaming.
Users sometimes report a problem about a partial display of stereoscopic content: the top third of the screen shows either an ordinary 2D image or a stereoscopic image with a high level of visual artifacts. I have not spotted this problem with any monitor I have tested including the GD245HQ and I guess this problem depends on the computer rather than on the monitor because owners of different monitor models complain about it.
When the response time compensation is turned off, the GD245HQ slows down, its average responsiveness increasing to 12.9 milliseconds (GtG) with a maximum of 25 milliseconds. It is impossible to use 3D glasses then. The 3D glasses only have some 8 milliseconds between the frames, so in order to deliver an artifacts-free stereoscopic image the monitor must keep the transition between two frames as short as 3-4 milliseconds.
The Acer GD245HQ would be a good 3D monitor if its firmware flaws didn’t spoil its image quality in 2D mode. There is no simple and reliable solution of that problem and, judging by the lack of improvements (the GD245HQ hasn’t changed in this respect over half a year of mass production) and official reaction from Acer, the manufacturer doesn’t think it to be a serious issue.
To avoid this problem, you should check out the GD245HQ sample you are going to purchase has normal image quality in 2D mode in the left part of the screen.