ASUS ProArt Display PA27UCX-K 27" 4K HDR Mini LED PC Monitor, 97% DCI-P3 99.5% Adobe RGB 100% sRGB, DeltaE<1, IPS, USB-C HDMI DP, 1000nits, w/X-rite Calibrator, Compatible with Laptop & Mac Monitor

I got the monitor from Amazon Wearhouse Deals in 'Like New' condition. Its default contrast setting is 80/100. The monitor is power limited, so when you take a white word page and blow it up to full screen, it decreases brightness, to keep power consumption low. This is why Linus Sebastian's review reported accurate δE at a small screen portion and poor δE full screen. But do not trust misleading reviews. Linus isn't as bright as his monitors. Reduce contrast to 50/100 or lower, and this issue is gone. After calibration in lower contrast, I measure an average δE less than 1.0. This is exquisite accuracy.Until you move the colorimeter to a different part of the screen. The Asus OLED suffers from uniformity issues. 50% gray looks patchy. 100% white shows shades of pink or red. This can happen with consumer OLED TVs, but not what is expected for a $4K monitor. We are being charged $1 per pixel to beta test premature inkjet printed OLED technology. Not acceptable. My 2014 Sony PVM A250 OLED is perfectly uniform.On the plus side, this display is very accurate at low brighness/contrast and discerns shades of gray very well. This was very important to me. Much more accurate than the Sony PVM A250 OLED (which crushes shades of gray at low brighness, they all look black). Some people, like Linus Sebastian, enjoy bright monitors, but I don't fancy a torch shining into my eyes. I prefer to work at a comforable low brightness, while keeping high accuracy. This monitor looks like a photograph, perfectly accurate without too much light hitting your retina. It can easily distinguish between all shades of gray, unlike my Sony PVM OLED. I can thus use the Asus OLED at much lower brightness and work much more comfortably. With the Sony, I have to increase brightness too much to discern different shades of gray, which makes it tiring and uncomfortable to use. This is why I prefer the Asus OLED over my Sony PVM 250 OLED, despite the uniformity issues of the former.Finally, 4K @ 60Hz is hard to push for all Intel GPUs. You will need a computer or laptop with a discrete, modern AMD or Nvidia GPU. Otherwise you will see 4K @ 30Hz, which is horrible, or you will have to reduce resolution. Unfortunately, lower resolutions look horrible in this monitor. It would have been better if Asus made this monitor at 1080p native resolution. You do not see 4K pixels at 21.5", so anything beyond 1080p is useless.UPDATE 1: I received a replacement. Same uniformity issues. Seems a problem with OLED technology. LG OLED TVs have it too. The replacement also has a new problem. Every minute or so, it displays a message 'power saving' and dims the screen. A minute or two later, the screen goes black, while I am writing this review, or watching a youtube video. Turns out the Human Sensor is defective and turns off the monitor, thinking there is nobody present. The issue can be avoided by turning off the Human Sensor in the monitor settings, but the replacement went back.I ultimately decided to keep the original monitor as the uniformity issues are difficult to notice. I really enjoy the accuracy of this monitor at low brightness, as I can still discern dark grayscale without having too bright white that burns my retina. Its lack of backlight makes it really comfortable to use. My visual cortex is incredibly relieved and for me this is totally worth the price tag.Update 2: I've been using this for several months. It is so comfortable, even for editing text, I don't want to go back to an LCD monitor.

I purchased this for gaming. When I first set it up and connected it to my computer I had the same problem the other reviewer Babis had. After being on for about five minutes I got a message that said power saving. The screen dimmed 50 percent. Then a minute later I got another message power saving. Screen dimmed another 50 percent. Then a minute later it went black and turned off. This happened on the second one Babis had and he thought it was defective and sent it back. These monitors are individually calibrated at the factory so it seemed strange to me that monitors were being shipped with this defect. I went all through the OSD menu and found two items. One was ECO mode which by default is turned off. I also found something called Human Sensor which was set low. I set ECO mode ON and I set Human Sensor OFF. That was the end of the screen dimming problem. My one big complaint with this monitor is a total lack of any instructions or manual. There is nothing except a single page showing how to turn it on and setup the stand. They also include the calibration results done at the factory but no instructions. I was ready to send this one back too until I dug into the OSD menu and figured out how to stop the screen dimming. I wonder how many of these have been returned as defective due to this issue.Now on to performance. Batis did a great review so I am just going to comment on my use. I set my brightness level at 50 percent, contrast at 45 percent and saturation at 35 percent. I have no dimming issues at all with all white screens like a word document and the screen is at a very comfortable brightness level for regular work and gaming. Now on to gaming. I fired up Fallout 4 which I just recently started playing through again with a whole bunch of new mods. As the game started where I had left off it was night in Boston. This is where my jaw dropped. I could see every detail in the dark. I have now spent two days playing Fallout 4 with this monitor and I do not think I could ever go back to a regular LCD display. The picture quality is amazing. The picture looks so real it draws you in and best of all after playing for four hours my eyes felt great. I am happy I purchased this as it will make my gaming more enjoyable. I just hope they can at some point figure out a way to crank out OLED TVs and computer monitors at a lower price.

full disclosure, the first one I received, out of the box had a 20% failed panel (defective, a bummer, but it happens) - my first attempt to return/replace it by Amazon was a mess (took over an hour to get nowhere), but the second Amazon rep I spoke to (I finally just hung up and called back), she got it done within 10 minutes, super easy!! The second panel, worked, is working 100% FRICKING AMAZING!!! I run 3 monitors, and thought I could just replace the "main/middle" one... the others two are so dim (and they are Dells, top of the line), but by comparison to this monitor, it is like they are off... and they are also great... just not this great!! didn't really know how dark they are until they are next to this goliath!! like turning the lights on in a room! text / icons / videos - everything just explodes (RAZOR SHARP)!! it doesn't run very hot... it is nice to know that the colors I see on the screen are what the colors are supposed to look like (if professionally done), and also see the color issues with home videos between different cameras - this thing (thus far), is like a rock! stupid expensive... but since it is trying to fight with Apples Cinema Display and Apple is fighting with reference displays ($30k+)... makes sense... at least today. I did purchase the extended warranty... it is to expensive not to.- if there is a negative... when running a really dark screen (not a movie as those always seem fine), but like a dark background (dark mode), sometimes icons, specifically green ones, shift their colors around a tad, brighter green (always green of course)... but that "problem" seems to go away if there is more white on the screen (like a browser window / word / etc...) - this problem is most likely what separates the $30k+ from the ~$5k line. Another thing I notice about it, if I have a small white box in the middle of an all black screen... it is sometimes like the black is creeping in, dimming the corners of the white box, like bleeding in, I notice it... ideally, I would like it not to be there, but it wouldn't stop me from loving this monitor and wanting more of them!! any photo I open, anything like that looks 100%... it seems to only have issues when there is a almost completely black background (not a movie) and there is something tiny (in relation to 4k) on the screen... and issue or problem is not really what I would say... just a noticeable hiccup and it could be just this monitor or the mode I am in...Windows 10 defaults to HDR - that disables the ability to adjust the brightness by default.if you can get this beast - do!!!

Twice I received the -P version of the monitor, not the -PK. I even contacted customer support before the second monitor was shipped and was assured I'd get the -PK model. Nope, got the -P model. The difference between the two is a not-inexpensive color calibration tool. Otherwise the two models are the same (though the labeling of the mini-LEDs is different). So, if you order the -PK monitor, make sure you are shipped a -PK box so you don't have to spend extra money and time to get the X-rite i1 Display Pro calibration tool.Also, there is a similar monitor out from ASUS that is much better for gaming. The PA32UCX-PK only has 60hz, which is fine for photography and most video workflows.

The monitor works well intermittently but there are two major issues:- The backlight is bad at times. This only happens in Dolby HDR for me at the moment. Sometimes the right half is dark. Other times the left half is dark. The halves are not off entirely but it looks like there is some sort of ghosting or memory effect. The picture I took showing the half-white / half-gray content is the playback of a 100% white video. Note that the gray on the screen is not a reflection. That is what the video appears like on the screen.- The screen appears to have a cooling system consisting of one or more loud fans. When these kick in, the unit is disturbingly loud. Much louder than a modern workstation.I will return this unit.