Picture Quality

The Cooler Master Tempest GP27Q features an AU Optronics 10-bit (8-bit + FRC) Quantum Dot UltraSpeed IPS panel capable of displaying 16.7 million colors. The panel can, in fact, be pushed to display 10 bits of color per channel by using Frame Rate Control (FRC), a method of temporal dithering to create a perception of 1,024 individual shades of RGB color (1.07 billion colors in total). Unless you're a creative professional with an established end-to-end 10-bit color workflow, you shouldn't lose sleep over the 8-bit+FRC nature of this monitor.

Quantum dots should be very familiar to everyone who's into television technology, where they've been actively used for more than five years. Samsung, in particular, leans into them as their entire QLED TV lineup featured Quantum Dot panels, which they considered so good that they made a point of steering clear of the OLED technology. This, of course, changed this year after Samsung released their QD-OLED panels, but those too again feature Quantum Dot technology, which is what the "QD" in the name stands for.

In short, quantum dots are semiconductive nanocrystals measuring 2–10 nanometers which are able to produce pure red, green, and blue light. Their exact color is determined by the number of atoms within. When light is shone on a quantum dot, it absorbs the light and reemits it at a specific wavelength or color. The wavelength of the light emitted by a quantum dot depends on the size and composition of the particle. By carefully controlling the size of the quantum dots and the material they are made of, it is possible to produce a specific range of colors, from deep reds to vibrant blues and greens. Quantum dots are applied to a sheet of film located between the backlight and panel/color filter. The quantum dot enhancement film then tries to improve the color gamut. The Cooler Master Tempest GP27Q uses blue backlight LEDs. Their light passes through the Quantum Dot layer, which gives the panel 98% DCI-P3 color coverage, according to the official technical specification sheet. We'll test that momentarily.

Just as importantly, the Cooler Master Tempest GP27Q is equipped with a Mini-LED FALD (Full Array Local Dimming) backlight system. It consists of 576 local dimming zones, which can be individually controlled to achieve deep blacks, very bright whites, and vivid colors in general. The key difference between Mini-LED backlight systems and traditional FALD backlight systems is the granularity. With as many as 576 controllable dimming zones on a 27-inch panel, the backlight of the Cooler Master Tempest GP27Q can adjust to the content being displayed on a small part of the screen.

The local dimming feature of the Tempest GP27Q is disabled by default, so do keep in mind that you have to activate it in the OSD should you decide to use it, which is a must if you plan to consume any kind of HDR content. The corresponding setting is found in the Advanced > Local Dimming menu. There are four options to choose from: Off, Low, Medium, and High. For standard dynamic range content, it makes little to no sense to use local dimming. You'll occasionally get weird issues in high-contrast areas, and the color accuracy will be subpar. In short, activate local dimming only if you're using the Tempest GP27Q in HDR mode.

Everything mentioned above amounts to a monitor that's fully equipped to display HDR content properly: it has a FALD backlight, a wide color gamut, and high peak brightness, with the specified HDR peak reaching up to 1,200 cd/m².

To test the picture quality of the Cooler Master Tempest GP27Q, I used a combination of the X-Rite i1Display Pro and DisplayCAL, a powerful software solution for display calibration and profiling, which is entirely free to use, assuming you own a supported colorimeter.

Picture Quality at Factory Settings

The picture quality of the Cooler Master Tempest GP27Q at its factory defaults was tested right after plugging the monitor in and allowing the panel to warm up for about an hour. The out-of-the-box picture tuning strikes me as less-than-stellar. The brightness is set to 27 in the OSD, which results in an actual panel brightness of 277.9 cd/m². The colorimeter also showed a reasonable contrast ratio of 973:1 but with a severe white point deviation; instead of 6,500 K, the white color temperature was 8,726 K on the review sample of the monitor, resulting in a picture with a heavy bluish tint. The color profile is set to User1 by default, and the color temperature is set to User as well, but with no adjustments to any of the three primary color channels.

A 27-inch 2560x1440 panel has a pixel density of 109 PPI, so its sharpness is very good. There's enough screen real estate to work in two windows at the same time without having to zoom out to the point of discomfort.


The measured out-of-the-box gamma had an average value of 2.43, and the corresponding measured curve shows a severe deviation from the reference curve. The actual gamma is constantly much higher than it should be, resulting in crushed blacks and lost details in dark parts of a scene, as the shadows are interpreted as darker than determined by the input signal.


As for the color accuracy, the out-of-the-box ΔE on the review sample of the Cooler Master Tempest GP27Q, relative to the sRGB color space, is 5.02, with the maximum ΔE climbing up to 9.85. The gray tones are somewhat accurate, but the colorimeter caught some substantial inaccuracies in red, blue, and green color tones.


The Tempest GP27Q offers sRGB, Adobe RGB, and DCI-P3 color space emulation modes (Color Adjust > Color Space menu), so I was hoping to get a vastly improved sRGB performance with the sRGB mode active, especially in the color accuracy department. While there were notable improvements in the grayscale color accuracy, the rest of the color spectrum still looks poor (the measured average ΔE is 4.32). The measured white point is even higher than before, climbing all the way up to 9,209 K, making the picture look even more bluish. The gamma tracking is greatly improved, but it still makes no sense to use the sRGB emulation mode in its default state. The good news is, activating the sRGB color space doesn't lock us out of adjusting the brightness or color temperature (at least not after the December firmware update), so it's entirely possible to bring the color temperature down to what we want – as close to 6,500 K as possible.

From what we saw up until this point, it's obvious that the factory settings on my sample of the Cooler Master Tempest GP27Q are somewhat of a mess. Luckily, the OSD offers the tools needed to address many of the aforementioned issues, so our first order of business is to do exactly that. After a lot of experimentation and testing, I found out that the best performance, relative to the sRGB color space, can be obtained by manually switching the monitor to sRGB mode (Color Adjust > Color Space > sRGB). Then I had to sort out the color temperature. This is done in the Color Adjust > Color Temperature menu, where I had to select the User Color option and then reduce the Green channel to 49 and Blue to 43 while leaving Red at 50. Since I usually aim for a screen brightness of around 250 cd/m², which I find ideal for combined daytime and nighttime usage, I also had to reduce the brightness to 26, but you should change it to your preference (Picture Setting > Brightness). Just don't push it too far, as the Tempest GP27Q can reach more than 600 cd/m² in SDR mode, which you shouldn't expose your eyes to for an extended period of time. Let's take a look at what happened after this single change was conducted.



With the aforementioned tweaks, we greatly improved the measured color temperature, bringing it from 8,726 K to 6,487 K, and removing the prevalent blue tint from the image quality. There were also massive improvements in gamma tracking, and color accuracy improved too, although it was still far from perfect. The measured color accuracy can be explained by the sheer width of the color gamut of the Cooler Master Tempest GP27Q. When displaying regular SDR content, the colors are noticeably oversaturated, and there's not much you can do about that other than calibrating the monitor or focusing on using it in HDR mode.


In terms of color gamut, the Cooler Master Tempest GP27Q is quite impressive. I measured a 99.8% coverage of the sRGB and 98.5% coverage of the DCI-P3 color space. The gamut volume equals 171.7% for sRGB and 125.1% for DCI-P3 color spaces, respectively. The measured Adobe RGB coverage is 97.6%, with Adobe RGB gamut volume reaching 118.3%. When looking at these numbers, it's obvious that the Cooler Master Tempest GP27Q offers a lot of versatility for users who use multiple color gamuts when working on their PC.


This is what the luminance and color uniformity of the Cooler Master Tempest GP27Q look like when measured at 25 different patches across the panel. Please click on the image to see it in high resolution and examine the data in greater detail. The luminance uniformity is fantastic, one of the best I have ever measured, clearly displaying the quality of the integrated Mini-LED backlight system. The same is true for contrast deviation, while color uniformity is somewhat problematic in the bottom left and far right side of the panel. Luckily, it's nothing too severe; my colorimeter picked up maximum deviations of ΔE 4.08 and 4.15, respectively.

Picture Quality After Calibration

I calibrated the display using the X-Rite i1Display Pro colorimeter and the DisplayCAL software solution. The initial profiling and calibration were done with the luminance target set to 250 cd/m², which presents a happy medium for a comfortable combined daytime and nighttime usage. The calibration was conducted with the adjusted settings which I've listed above.

Here's what we get after calibrating the monitor.



A proper calibration results in excellent color accuracy and almost perfect gamma tracking. The average color accuracy ΔE went down to 0.4, and the maximum measured ΔE is 1.7, which is a substantial improvement to the ΔE values measured before calibration. In calibrated state, the Cooler Master Tempest GP27Q can be used even for color-critical work.

HDR Performance

Having a Mini-LED FALD backlight system, high peak brightness, and wide color gamut, the Cooler Master Tempest GP27Q is fully capable of providing an excellent HDR performance. This is an obvious strong suit of this monitor and one of the main reasons it's likely to be a popular choice amongst more demanding gamers.

To activate HDR mode, you must set it to Auto in the OSD (Advanced > HDR > Auto) and then open Display settings in Windows, where you'll find the HDR toggle. This needs to be set to On. Finally, activate the monitor's local dimming technology (Advanced > Local Dimming > High).

Activating HDR locks you out of adjusting some of the color settings. Gamma is locked to 2.2, the color domain is set to Auto, and the predefined color space is BT.2020. You can play around with color temperature, although it's not possible to adjust the gain of individual RGB channels. You can (and should) set the color temperature to User Color. That sets the channel gain to the default value of 50. While far from ideal, it's the best available setting in terms of getting the white point to a reasonable level.

When it comes to HDR gaming, the Cooler Master Tempest GP27Q shines. It runs circles around monitors that don't have a Mini-LED FALD backlight system and surpasses many that do. I measured a peak brightness of up to 1,277 cd/m², with a contrast ratio reaching beyond 100,000:1 due to the black level being as low as 0.0124 cd/m². Combined with a wide color gamut panel, this makes your games look rich, vibrant, and impactful. If your PC has enough horsepower to offer high framerates at 2560x1440 with ray tracing turned on, you'll be treated to some of the nicest in-game visuals you've ever experienced.

On the flip side, while the HDR performance of the Tempest GP27Q is quite impressive, the overall experience of living with HDR in Windows is, to put it mildly, less than ideal. You would assume that setting the HDR feature to Auto in the OSD will have the monitor and Windows automatically switch between SDR mode when you're not gaming and HDR mode when an HDR input signal is detected. That's not the case, though. To get the monitor to properly display HDR content, you have to manually turn on the appropriate option in Windows' Display settings menu. Keeping it on all the time isn't a great solution if you plan to use the monitor for color-critical work, as color accuracy takes a hit in HDR mode, and you're unable to adjust various other picture quality-related options or fine-tune the color temperature. If you do end up using HDR permanently, keep in mind that you can expand the HDR menu in Windows to access the SDR content brightness slider, which can help you increase the screen brightness when HDR mode is active, but SDR content is being displayed.

Cooler Master must also iron out some remaining HDR-related bugs in their firmware. The one that annoyed me the most was an unexplainable drop in picture brightness whenever my PC woke up from sleep with HDR mode active. The SDR picture brightness would go down from 313 cd/m² to 111 cd/m² on my sample of the monitor. To restore it, I had to open the OSD, go to Picture Setting > Brightness, reduce the brightness from 100 to 99 and then bring it back to 100. Only then the SDR brightness would go back to 313 cd/m². For reasons unknown, the firmware obviously doesn't reapply the OSD brightness setting after returning from sleep.

Summed up, the user experience of HDR gaming on a PC continues to be lackluster. At the same time, if you're not deterred by the everyday quality-of-life issues described above, the Cooler Master Tempest GP27Q will provide you with an excellent visual experience.

Backlight Uniformity

To give you an idea of the backlight's uniformity, I set the monitor's brightness to 250 cd/m² before taking a photo of the panel in a completely dark room. I did my best to find a combination of the ISO value and shutter speed that would capture the screen in a way that has it look as close to what my eyes were seeing in real life.



There's some backlight bleeding around the top and bottom left edge of the panel. Still, it is mostly unnoticeable when using the monitor unless when playing an exceptionally dark game or watching a movie with a lot of shadow content.

Viewing Angles

The viewing angles of the UltraSpeed IPS panel built into the Cooler Master Tempest GP27Q are excellent. There's no visible shift in colors when changing sitting positions.