Out of the Box Performance
The VS239H-P uses an IPS panel capable of producing 16.7 million colors. The diagram below shows the monitor's color space (red triangle) against the sRGB color space (green triangle). It's evident that our test unit matched the sRGB space well, going beyond the greens, and was just a bit short in the blue shades.
Luminance was recorded at a high 261cd/m2. Considering that brightness was set at 100%, we weren't surprised with this reading. Black luminance came up to be 0.45cd/m2. These gave us a static contrast ratio of about 576:1. Gamma was spot-on at 2.20; there are no gamma presets available in the OSD menu. Color temperature was also spot-on at 6,500K.
With the exception of the sRGB preset, the other video modes gave us a color temperature of 6,500K. Surprisingly, we got a reading of 7,400K for the sRGB mode. Besides the User Mode where each of the R,G, and B gains are set to 100%, there are three more color temperature presets: Cool, Normal, and Warm. We recorded values of 13,400K, 9,400K, and 7,500K respectively.
All in all, it looks like the Standard preset is a good mode to base any calibration on.
There wasn't any part of the screen where the luminance deviated from the center by more than 8%; most parts kept within 4%. The top half of the screen was ever so slightly dimmer than the bottom half; you'd be hard pressed to notice it under normal circumstances.
Our preference is to calibrate the monitor to a brightness of 120cd/m2. To get the monitor down to this level of white luminance required us to drop the brightness setting of the VS239H-P from 100% to 35%. Credit to the fairly accurate Standard preset, color-accuracy-wise, the difference before and after calibration wasn't night and day. Post-calibration, black depth was at a good 0.24cd/m2; contrast ratio was recorded at 509:1.
We then proceeded to run some tests using DisplayMate, and we were happy with what we saw. Sure, we spotted slight banding at the extremes of the spectrum, but for the most part, gradients were smooth.
The ASUS VS239H-P has power consumption specs of <40W during use, and <1W during standby and power off modes. Out of the box, we measured a power consumption of 34W during use. (Remember, it was using the Standard preset with brightness cranked to 100%.) Switching to Eco mode lowered the power consumption to 22W. After calibration, during which we turned down the brightness down to 35% to achieve our preferred luminance of 120cd/m2, power consumption was measured to be at 21W. During standby mode, the draw was 2W; there was still a small 1W draw when the monitor was turned off.
Depending on your region, your friendly retailers may be carrying either the VS239H or VS239H-P. According to ASUS, the latter carries the EPEAT environmental certification, something that's required for the EU market. While there's no need to have this environmental rating for the Southeast Asia market, ASUS Singapore also carries the VS239H-P.
While both models share largely similar specs, there are a couple of differences. The VS239H has a response time of 14ms, the VS239H-P a response time of 5ms (gray to gray). Also, the former doesn't have the Trace Free feature that the latter has. For those interested to know, there's also a VS239N model. This model has a 14ms response time, and doesn't come with Trace Free as well. It also drops the HDMI input and 3.5mm earphone jack.