You've probably seen the news that came out of CES a few weeks ago: 4K ultra-high-definition monitors for under $1000! Dell announced the P2815Q, a 28-inch 3840x2160 panel for just $700, and you can already buy it. Lenovo and Asus both announced their own sub-$1000 4K panels at the show--the Lenovo ThinkVision 2840m and Asus PB287Q, both shipping in spring or summer for $800 and both offering that 28-inch 4K experience. But are any of them good enough to buy?
Nope. Not yet.
More like Twisted-No-Thankyou
All the sub-$1000 4K monitors announced so far--at least the ones we have any panel information on--use twisted-nematic (TN) displays rather than in-plane-switching (IPS) panels. A TN panel can have quicker refresh rates, but everything else about it is inferior to IPS: the viewing angles are bad, the colors are more washed out, and it inherently can't reproduce as wide an array of colors as an IPS panel, so it's not accurate enough to use for photo or video editing. (More on the difference in this previous column.)
TN panels are still popular with twitch gamers because they can have much quicker pixel refresh times than IPS monitors, which can be important in fast multiplayer shooters. And indeed, Dell advertises a 5ms refresh rate, which on the surface seems fast enough for gamers. But that leads us the next problem with Dell's 28-inch 4K monitor, and possibly the other two as well.
It's A Series of Tubes
The killer flaw of the Dell P2815Q panel: it's capped at 30Hz when it's at full 3840x2160 resolution.
Turns out the way Dell is able to sell a 4K panel at $700 is by limiting the screen refresh rate. A 4K panel shows the same number of pixels as four 1080p monitors, and that's more than most display protocols can push through in a timely fashion. HDMI can't do it yet--HDMI 1.4a, which is what's on even the latest video cards, can do 3840x2160, but only at 30Hz. And that's the killer flaw of the Dell P2815Q panel: it's capped at 30Hz when it's at full 3840x2160 resolution. So that's kind of a dealbreaker: who wants to game at a locked 30fps? The P2815Q's refresh rate goes up to 60Hz if you drop the resolution down to 1920x1080, but a) 1080p looks pretty bad at 28 inches, and b) if you're going to game at 1080p, you might as well get a cheaper monitor with a higher refresh rate.
Now, wait, you say, HDMI isn't the only port on that Dell monitor. There's also DisplayPorts. Several of them! Yep, the Dell has DP and mini-DP inputs, and even an DP output port with MST, so you can daisy chain monitors. MST stands for Multi-Stream Transport, and it's the mechanism by which some 4K panels can run at 60Hz over DisplayPort. Just not this one.
According to Chris Heinonen, monitor guru at AnandTech and longterm A/V reviewer in his own right, you can run a 4K monitor from a DisplayPort 1.2 output, as long as the monitor supports MST. This is how Dell's much more expensive 32-inch UltraSharp UP3214 runs at 60Hz: it uses DisplayPort's Multi-Stream Transport so that it appears to the graphics card's DisplayPort chip as two separate 1920x2160 screens. As Chris says, "It's a bit of a hack." Of course, the UltraSharp UP3214 uses a beautiful IPS panel and costs $3500. So. Probably don't buy that either.
Asus claims that their $800 28-inch 4K panel, the PB287Q, will have a 1ms response time and 60Hz refresh rate at 4K resolutions. If that's true, Chris says, it means the PB287Q uses DisplayPort 1.2 with MST to do the same trick that the Dell does, and that could explain why it's $100 more expensive than the Dell. "If the Asus does 60Hz at 4K," Chris says, "then it's the one most worth getting."
Not For Gamers
Note that he said that it's the one most worth getting, not that you should get one. "I almost always recommend against TN except for hard core gamers, since you can get a nice 1080p IPS display for around $200 if you look around. TN is useful for gaming but that’s on the displays that run at 120Hz or 144Hz for a smoother experience."
Seriously, don't get a 4K panel for gaming right now. A 3840x2160 picture has four times as many pixels to push as 1080p. Unless you're running multiple GTX 780 Tis or Titans, your machine will struggle to output playable frame rates at resolutions that high without dropping the output quality considerably. So you'll be dropping your play resolution down to get good frame rates, negating the whole point of a high-res screen. And according to Chris, lowering the output resolution could even introduce lag from the monitor's scalers.
"I was pretty impressed with the G-Sync demo at CES, that technology interests me more from a gaming standpoint. Combined with a display that supports black frame insertion (BenQ, for example) you can get less blurring with no tearing or other artifacts from V-Sync being disabled. If gaming was my main focus, I’d look at those technologies instead."
Not For Graphics Professionals Either
As I mentioned above, TN panels don't reproduce colors as accurately as IPS panels, so they're not good for designers. Chris: "The color gamut is usually far lower (perhaps 30-40% of the sRGB gamut instead of 70-100%) so there are a lot of colors it just can’t reproduce. That’s going to make it less ideal for any sort of photo or video work."
If you've given up the idea of gaming on a 4K panel entirely, which you probably should have, you might still be tempted to get a 4K panel for desktop work. Which is fine, but you still have the poor color fidelity to deal with, as well as desktop scaling. Without desktop scaling, a 28-inch 4K panel's UI elements are pretty tiny. With desktop scaling, though, Chris loves it, comparing it to using a Retina MacBook Pro.
"It’s going to be really sharp if you run it at 150% or 200%, and so Word and Excel and everything will be great. For general productivity applications, it’s probably good."
Running at 150% scaling will give you the same effective real estate as 2560x1440, only sharper, and running at 200% resolution gives you the same UI size as running at 100% on a 1920x1080 monitor. I find that 1080p looks a little sparse at 27 or 28 inches, but 2560x1440 at 27 inches looks fantastic. So I'd aim for 150% scaling if I got a 4K desktop monitor.
"Probably" isn't Good Enough
We still have almost no information about Lenovo's $800 4K monitor, the ThinkVision Pro2840m. Lenovo's , another 4K monitor announced at CES, also has a 5ms response time, but there's no word on the panel type or refresh rate. It'll be $800 and come with HDMI and DisplayPort, um, ports, plus USB 3.0 and a flexible stand. It comes out in April. It's in the "probably not" category.
The Dell is a "no" and the Asus is a very qualified "maybe," but not for gaming or professional work. So you really shouldn't buy a 4K monitor right now, unless you work in an office and want the sharpest Excel spreadsheets you can possibly render on a panel.
If Not Now, When?
When should you get a 4K panel? Soon. Maybe even this year. HDMI 2.0 is coming this year, and it'll support 3840x2160 at 60Hz, although it'll take a while before HDMI 2.0 is available in monitors and video cards. It'll show up in 4K TVs and Blu-ray players first.
Chris recommends holding off until you can get an IPS 4K panel for under $1,000. One hopes by then that display technology--HDMI 2.0, better Windows support for multiple monitors with different pixel densities, and application support for super-high-res displays--will have caught up.