Cooler Master Tempest GP27U 160 Hz Mini LED 4K Review: Bright, Colorful And Speedy

As an image-quality geek, I look for one thing above all when evaluating displays —contrast. Dynamic range, the difference between black and white, is king. Get that right, and everything else falls into place. When CRTs and plasma panels left this planet, so did deep contrast. Self-emissive technologies can turn off individual pixels to produce a true black. LCDs cannot do this, but there is hope.

Today, we have LCDs that can do a passable imitation of a plasma or OLED panel. We know them as Full-Array Local Dimming (FALD) panels, and they come in two varieties: LED and Mini LED. That second one has become more significant of late. Though a premium technology, Mini LED has expanded the number of dimming zones possible. More zones mean better control over more and smaller pieces of the image.

Best of all, the newest 27-inch 4K panel from Cooler Master, the Tempest GP27U, comes out of the gate for around $800. It features 576 dimming zones, a Quantum Dot film for wide gamut color, 160 Hz refresh rate, Adaptive-Sync and HDR 1000. Let’s take a look at this highly qualified candidate for our best 4K gaming monitors list. 

Cooler Master Tempest GP27U Specs

The GP27U delivers a lot of value at the $800 price point. Mini LED usually delivers high brightness, which is here with a VESA DisplayHDR 1000 certification and an actual peak of over 1,200 nits (which I verified in testing). I also discovered infinite black levels in HDR mode thanks to a backlight that switches off completely, when necessary (more on that later). A Quantum Dot film produces a huge color gamut. I measured over 113% coverage of DCI-P3 and an excellent attempt at Rec.2020 with over 81% of that color space. You also get presets for sRGB, Adobe RGB and DCI-P3.

Among 4K screens, 144 Hz is the usual maximum speed but the GP27U manages a reliable 160 Hz refresh rate. The only caveat is that you must turn off Adaptive-Sync to go above 144 Hz. But Cooler Master provides a superb overdrive option with multiple presets and a 100-step variable setting, which is quite rare. It lets you dial in the perfect balance between clear motion and ghosting.

Additional conveniences include aiming points and timers along with nicely diffused LED lighting in the back. A USB-C port can accept video and serve as the anchor for a KVM feature that’s managed from the OSD. A solid stand and rugged build quality round out a premium package that at this writing, undercuts the competition by a few bucks.

Assembly and Accessories

The GP27U comes out of its carton in three pieces with a solid metal base, sturdy upright and a panel that snaps in place. The packaging is flexible foam, not the crumbly stuff I loathe. Thank you, Cooler Master. Assembly is easy since no tools are necessary, and it’s a sturdy piece. Along with a large external power supply, you get HDMI, DisplayPort, USB-C and USB-A/B.

Product 360

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The GP27U has a thin flush bezel around the image with just 8mm of frame around the top and sides. The bottom trim is 17mm with a tiny power LED on the right and an equally tiny Cooler Master logo in the center. Powering on reveals the rounded hexagon that lets you know the maker, followed by a bright and colorful image that’s razor sharp and free of any grain associated with the anti-glare layer. Don’t be fooled by the photo above; it isn’t shiny. The finish is matte, like nearly every other computer monitor. The first thing you’ll notice is the breathtaking color. You’ll see why that is when you read the test results on page four.

The stand is a single round pole with a large metal base, also in a hexagonal shape. It’s nearly 11 inches deep, so there’s no danger of the GP27U falling over. Ergonomics include 110mm height, -5/20 degrees tilt and 15 degrees swivel. You also get a 90-degree portrait mode. Movements are firm and free of play, befitting a premium display. Unsnap the stand to reveal a 100mm VESA mount for which you’ll have to provide your own fasteners.

Reach around the back right, and you’ll find the GP27U’s sole control, a tiny joystick. It covers all monitor functions and navigates the OSD. Also in the back is an LED ring around the stand’s pivot point, along with two additional strips flanking it. The only control of the light show is to turn it on or off. It smoothly changes color through the entire spectrum and casts a nice glow on the wall behind the monitor. Several chiseled accents round out Cooler Master’s subtle and effective styling cues.

The input panel includes two HDMI 2.1 ports plus a DisplayPort 1.4 with Display Stream Compression (DSC). The USB-C input accepts video too, mimicking the DP functions. An upstream and two downstream USBs handle the KVM feature, which can be set up in the OSD. You also get a 3.5mm audio jack with two three-watt internal speakers. They are typical monitor speakers with a small but clear sound concentrated in the upper midrange frequencies.

OSD Features

The GP27U’s OSD is styled for gaming with info bubbles at the top showing resolution and the status of Adaptive-Sync, HDR, and overdrive. On the right is a refresh rate indicator ticked off in fps units. There are plenty of options for tweakers organized into six sub-menus.

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After the input selector, the GP27U’s Picture menu is where you’ll find luminance, black stabilization (shadow detail enhancement), and the nine picture modes. You might think Standard is the default, but it’s User 1, which has all the calibration options needed for a very accurate picture.

Moving to Color Adjust, there are four color temp options plus a precise user mode with RGB sliders. Five gamma presets range from 1.8 to 2.6, and you can adjust hue and saturation for all six colors. Color Domain refers to signal format, RGB or YPbPr. Auto is the correct setting there. Color Space lets the user choose Adobe RGB, sRGB, DCI-P3 or Rec.2020. If you want to keep picture controls accessible, choose Auto. The Blue Light Filter warms the image to help reduce eye fatigue.

Gaming Setup contains one of the best overdrive menus you’ll find anywhere outside of a Dough Spectrum monitor. In addition to the four presets, the User option has a 100-step control. You can get a perfect level of blur reduction without ghosting. I also had good luck with Dynamic and Advanced. The GP27U’s video processing is top shelf. Gaming Plus offers a timer, aiming points, and an fps indicator.

You can set HDR to Auto in the Advanced menu so that it will switch between formats without user intervention. Local Dimming enhances contrast for SDR but also makes the picture extremely bright though you can compensate by turning down the brightness slider. It’s a must for HDR if you want the best possible quality. I measured zero black levels because any setting of Local Dimming, even Low, turns off the backlight when a black pattern is displayed. This menu also has the KVM setup, where you can bind video inputs and USB ports to accommodate multiple systems connected to a single GP27U.

Cooler Master Tempest GP27U Calibration Settings

In the GP27U’s User 1 mode, I found a slightly cool grayscale and gamma that rode just a tad under the reference line (too light). A few adjustments to the RGB sliders took care of the first issue, but gamma is still a little light. Higher presets make the picture too dark, so I suggest leaving it on 2.2. I had to turn down contrast two clicks to solve a clipping issue at 100% brightness. Though set to Auto, the color gamut uses its full volume for all content, SDR and HDR. This is great for HDR, but SDR images are extremely vivid. Most users will prefer this look, and the GP27U is certainly very colorful. But if you want sRGB or DCI-P3, you can go to the Color Space sub-menu and pick your preferred gamut. My instrument-derived settings are below.

HDR signals reveal three additional picture modes. User is the default, letting you adjust brightness and contrast if you find the 1,200-nit peaks too bright. It’s very color-accurate, so no further adjustments are required. I recommend setting Local Dimming to Low in HDR mode for the best luminance tracking.

Gaming and Hands-on 

The GP27U is a gorgeous monitor right out of the gate. With a larger color gamut than nearly everything I’ve seen of late, it is awash in vivid hues. The picture is razor-sharp with superb contrast. Working in SDR mode with productivity apps, it looks fine with the local dimming turned off and better set to Low. I didn’t see any downsides like clipped detail. If you’re accustomed to an sRGB monitor, the extra color will look a little overblown at first. However, since there is no loss of detail or dynamic range, it’s OK to use the full gamut (113% of DCI-P3) for everything. I reached for the sRGB mode a few times when working in Photoshop, but the extra color is nice for general use.

A 27-inch 4K monitor has tremendous pixel density, 163ppi, more than just about any other screen outside a high-end laptop. That difference can be seen, even when compared to a 32-inch 4K monitor. I am a fan of large panels, but the fine detail and sharpness of the GP27U are as addictive as its price is attractive.

I ran my response and lag tests at 160 Hz, but I saw a few frame tears when viewing the G-Sync pendulum test, so I dialed the GP27U down to 144 Hz to engage Adaptive-Sync. It worked with both FreeSync and G-Sync platforms equally well. Setting up the overdrive was easy, with many fixed and variable options. For most content, Advanced kept the blur at bay with no ghosting. I also tried the User mode set to 67 out of 100. This gave me a subtle improvement. This is one of the few monitors with a user-tweakable overdrive, and I recommend taking advantage if you buy a GP27U.

Gaming was a treat, especially in HDR mode, where the contrast and color were simply stunning. Blacks were very deep with just the right feel for night scenes, while detail was rich in highlight and shadow areas. The HDR User mode was ideal with the brightness slider maxed at 100, allowing the occasional 1,200-nit highlight to slip through but it was never harsh. Local Dimming worked best on Low; higher settings made the picture uncomfortably bright, and some detail at the extremes of the scale was lost.

The GP27U’s immense color gamut was on full display in Doom Eternal. The red primary shone through the most with bloody hues that were almost too realistic. Maps with greenery and vegetation had a natural and three-dimensional look with warm earth tones and vivid textures. Motion processing was beyond reproach, and I saw no blur or tearing. I played at 144 Hz and managed to peg the fps meter a few times. Though I still gravitate to 240 Hz QHD screens with their screaming frame rates, the sharp detail made possible by such high pixel density is compelling. A monitor like this is a great reason to put a large chunk of your build budget into speedy video cards. High frame rates and high resolution are expensive but once you’ve experienced them together, it’s hard to go back. 

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