Modern display tech analysis for planning purchases

[donluca]

Thanks for the explanation!

Looks like G-Sync is the way to go then.

One more thing, then: besides MAME, where we have non-standard refresh rates, what is actually the lowest lag monitor for stuff which outputs the panel's native resolution and refresh rate?

[Xyga]

Many show under half-a-frame today, and a number of them very close to no lag at all, like the PG279Q, or some single-DVI input 1440p Korean models.

[Guspaz]

IIRC, LinusTechTips measured the PG279Q at 12.something milliseconds, did somebody else take measurements that show less than that?

[Xyga]

Yes tftcentral.
0.75ms for actual processing/signal lag, 3.25ms in total adding the average pixel response time.

[donluca]

Holy moly, the Asus PG279Q is ~700€! O_O

I looked into TFT Central and saw that the Dell p2414 which has an average of 8ms lag (which isn't bad) and it can even be used vertically and is ~200€ which is more reasonable to me.

[Guspaz]

8ms is the response time, not the input lag. The two are unrelated other than the fact that input lag is the sum of processing time and response time. That said, the measured input lag on the P2414H is 5.5ms, so maybe the 8ms reported by Dell is conservative, and either way it's a very low latency monitor.

The P2414H is a lot cheaper, but it only has 78% the viewable area, 56% the resolution, 36% the framerate, 71% the brightness, and a 100% slower response time. Not sure about input lag. The Dell also lacks speakers, and g-sync. From everything I see, it's a good monitor, but it's really not comparable to the Asus.

[Fudoh]

I looked into TFT Central and saw that the Dell p2414 which has an average of 8ms lag (which isn't bad) and it can even be used vertically and is ~200€ which is more reasonable to me

if you want compatibility for non-standard refresh rates (e.g. 55Hz) you need G-SYNC. No way around it. The Dell is certainly is a nice display (I got two U2414 ones), but it can't offer that.

[donluca]

After seeing the prices on those G-Sync monitor I decided I'd better be off with something cheaper (if I'll ever do the upgrade) and the Dell P2414H (and the one you mentioned, the U2414) looked like fine monitors to me at a good price.

For comparison sakes, I'm actually using a TV-Monitor, an LG M227WDP (which probably has a disgusting amount of lag) and an old Samsung SyncMaster 943. So, yeah, the Dell would definitely be a huge upgrade.

I'm curious how well regarded is lag-wise my iMac 27's own monitor. It's a 2560x1440 screen, middle 2011. I might go and look for some specs.

EDIT: looks like it's an LG panel. The specification says that the response time is 6.5 to 7.5 ms. Not too bad.

[BazookaBen]

EDIT: looks like it's an LG panel. The specification says that the response time is 6.5 to 7.5 ms. Not too bad.

Response time is not the same thing as display lag. Response time is just about how fast the pixel can change color, input lag is dependent on many more factors

[Ed Oscuro]

I should have a pg279q in tomorrow. I won't have a card that can run G-Sync for up to a week, but I should be able to share a few impressions all the same. You don't always have to buy the highest price - of course in the US we don't get the Euro exchange rate woes, so it's possible to snag one for $700, as I did. But it was an "open box" deal and I'll have to see how good / bad it is. Also be sure to stay up to date on Acer XB271HU deals, as it's priced identically and is much the same hardware.

And as a general tip on hardware buying - I just discovered that /r/eddit has a subforum called "buildapcdeals" or something similar, which shows deals on hardware. I didn't see the Newegg deal listed that I jumped on today, but buying Geforce 950/960 units is kind of weird P:

A couple things could use further explanation:

- These 1440p panels might have subpar performance with 1080p content. I'll try to measure this.
- For PC gaming, refresh rate is very important for minimizing input lag (i.e., 1/120th second is a smaller game loop than 1/60th second), but you need hardware and software that supports better-than-60 frames per second rates. For 1440p, that's 1.7 times as many pixels to push. In almost any 3D game that's going to result in a sizable performance question.
- I've never seen anybody fully explain how panel and monitor manufacturers classify panel response time, and thankfully there are independent reviews. But it should be noted that those figures could represent partial (easier) color transitions, or full ones (difficult). Real content is a mixture of these difficult and easier transitions. In the UFO and racecar type tests you get a pretty good idea how fast the LCD matrix springs back to normal in different colors. However, if you are doing some really dramatic scene changes (i.e., really fast camera panning where a lot of the content changes totally) then I'd expect things to fall apart even on better panels, but less than on a poor performing panel. On the other hand, even with a "slower" panel, with some types of scenes (i.e., 2D games) response times probably won't be so important because relatively little is changing from frame to frame and so intelligibility is going to be much higher.

Also the various reasons of G-Sync and FreeSync could be summarized like this:
- Eliminate tearing
- Eliminate framerate halving and reduce the performance gap with non-vsynced display
- Allow a fluctuating framerate with no input lag penalty... (allowing the highest level of performance possible)
- ...or allow arbitrary soft caps to be utilized (allowing the highest level of performance without stuttering, for consistent gameplay, or for other reasons)

"Soft caps" are set in the software for G-Sync and FreeSync (for Source engine games, "fps_max 144" or so should work - depending on the details of the game and driver version this might be really a setting of 120 or 143, or even 200 or 250 fps, etc.). I think the major no-no of adaptive sync is turning on v-sync in software, as that's handled instead by the software.

[donluca]

EDIT: looks like it's an LG panel. The specification says that the response time is 6.5 to 7.5 ms. Not too bad.

Response time is not the same thing as display lag. Response time is just about how fast the pixel can change color, input lag is dependent on many more factors

I know, this was said before, but this is all I could find about it and, relatively speaking, it's an interesting value.

[Ed Oscuro]

For IPS panels, some people say that the gaming panels are 5ms, others say they're 8ms, and in practice you might see - for a given transition - something even lower than the lowest value (I believe this is reflected in the TFT Central tests). For us, these arbitrary numbers don't mean much except as a rough way to decide whether one set is better than another; only seeing the panel in action (or photographs, as reviews do) is going to be really understandable for a person.

Generally speaking, the mixture of content in a scene means that you probably will be able to notice a new transition (as the panel starts to change to a new frame) unless you play a game that has some really tough patterns (like transitions of white to black and back again). At that point, the main way you'll notice response time is in how sharp transitions happen in the scene - a really bad panel with a tough transition will be hard to decipher in some games, while a fast panel will be much easier to read at a glance. Of course, like I said before - people were able to play 2D games at a fairly high level even on quite old LCDs, and the major problem was input lag in total, not the pixel response time so much.

When you get into FPSes and other genres where everything on screen changes from frame to frame, response time is more important.

[Guspaz]

Also be sure to stay up to date on Acer XB271HU deals, as it's priced identically and is much the same hardware.

It uses a very similar panel, but it's not the same one.

[BazookaBen]

I know, this was said before, but this is all I could find about it and, relatively speaking, it's an interesting value.

Why is it interesting though? The figure doesn't really give you an idea on how it will perform for games. I'm thinking ~8ms is a pretty typical response time for modern LCD's.

[Ed Oscuro]

Typically I see 1 or 2ms quoted for TN panels, and the new IPS panels seem to be quoted as 5ms or 8ms. Not sure if those are for the same panel types.

@ Guspaz: Do you have a source for that? TFT Central hasn't reviewed the XB271HU, but in every listed spec it seems to be rated identically to the PG279Q, except for some differences in the factory refresh rate overclocking (165Hz or just 144Hz with no overclocking). Just to be sure, I'm talking about the latest 1440p G-SYNC monitors from Asus and Acer, not the older versions or TN versions of the monitors, though even the slightly older Acer XB270HU seems to have much the same panel as well, which might be why TFT Central hasn't reviewed the -271HU revision.

I did note a comment somewhere describing the panels as having a different backlight glow color (and another comment denying this), but the Acer also has a slightly different bezel design than the Asus.

[BazookaBen]

One question I have for you guys, since I've been playing on PC CRT's all my live and I've never purchased a TFT monitor: Are any of the high-end gaming TFT's able to sync to any refresh rate you throw at it up to a certain limit (like CRT's)?

For example. I can run my CRT at 60hz, 62.32hz, 92.67hz, 56hz, 125hz, 75hz, 75.5hz (you get the picture). Are there any TFT's that have the same near-infinite range of compatiblity, or will the only sync to a select few, like 60hz, 144hz, 75, etc.

[Guspaz]

Typically I see 1 or 2ms quoted for TN panels, and the new IPS panels seem to be quoted as 5ms or 8ms. Not sure if those are for the same panel types.

@ Guspaz: Do you have a source for that? TFT Central hasn't reviewed the XB271HU, but in every listed spec it seems to be rated identically to the PG279Q, except for some differences in the factory refresh rate overclocking (165Hz or just 144Hz with no overclocking). Just to be sure, I'm talking about the latest 1440p G-SYNC monitors from Asus and Acer, not the older versions or TN versions of the monitors, though even the slightly older Acer XB270HU seems to have much the same panel as well, which might be why TFT Central hasn't reviewed the -271HU revision.

I did note a comment somewhere describing the panels as having a different backlight glow color (and another comment denying this), but the Acer also has a slightly different bezel design than the Asus.

I was referring to the Acer XB270HU against the Asus. The Acer XB271HU is out now, but costs about the same as the Asus (I see it only 10% cheaper than the ASUS). For the older Acer, the benchmarks are all different enough to indicate a very similar but not quite identical panel. Since the Acer came out something like 6-9 months earlier, that makes sense. Probably the new Acer is the same panel.

[Ed Oscuro]

Yeah, I was afraid we've not been really clear and exhaustive in our responses, so let me give a shot at it:

Yes and no.

Yes: G-Sync and FreeSync monitors are indeed intended to do just this, with the added benefit of being able to switch frequencies with each frame.

There are some limitations though: Where CRTs have phosphor decay time, LCDs have response time - and unlike phosphor decay this is controllable by what's called drive (voltage). That's where that "overdrive" term comes from. G-Sync and FreeSync seem to differ mainly in terms of how this is implemented: G-Sync monitors' nVidia scaler unit is said to include drive voltage control so that nVidia and manufacturers can set good performance throughout the range (something like a look-up table of values, I believe). I understand that FreeSync monitors, which don't have a similar component, might only have one voltage drive setting, or perhaps a couple, so the drive setting won't be correct at a different range.

I don't know if this is at all an issue for most FreeSync monitors, but in some there have been multiple FreeSync (refresh rate) ranges in an attempt to compromise between having a full range of refresh rates, and having good visual performance.

As an example, when launched the MG279Q's refresh rate was limited - through drivers, which can be hacked for the possibility of a larger range - to running from 35Hz to 90Hz, but you could also run it at up to 144Hz - just without the benefits of FreeSync (no frame syncing, no on-the-fly refresh rate fixes). I also seem to remember a monitor which had two selectable FreeSync ranges, but that could just be me forgetting that one range was with FreeSync off.

[Ed Oscuro]

I was referring to the Acer XB270HU against the Asus.

I (initially) wasn't, though, so let's be careful here. I specifically mentioned the XB271HU for this reason.

Between the XB270HU and the PG279Q - yeah, they're definitely different panels:
http://www.tftcentral.co.uk/reviews/con ... .htm#panel

However the XB271HU and the PG279Q likely share the exact same panel.

I did mess up on details of the XB270HU after your reply, though. TFT Central does show some differences, but they appear to be slight - the pursuit camera behavior of the pg279q looks slightly better - hard to say how dramatic it would be in use. Unfortunately their breakdown of the screens' respective input lag / response time appears based on a bit of speculation, apparently taking the manufacturer's stated pixel response time in order to break down how much input lag is due to processing and how much is due to pixel response slowness. Their performance on the chart is actually very similar, so if the question comes down to "I can get an XB270HU for much less than the newer screens, should I do it?" the answer should be yes, it's probably not a really big difference.

[Guspaz]

On Newegg, it's $920 for the XB270HU, $1000 for the XB271HU, and $1100 for the PG279Q. So the price difference between each hop is relatively small. It's definitely less, but I wouldn't call it much less.

[Ed Oscuro]

I don't know where you're seeing those prices from, but usually (including just seconds ago) the pg279q and xb271hu's sale price - what you actually pay, instead of the fake "pre-discount" price - have been $799.99. Sometimes Google reports weird prices, but I've never seen them anywhere near $1000. I've seen inflated prices around $800, and the units have sometimes been out of stock at Newegg, so they offer "deals" from other parties. Newegg even still has a $699.99 Open Box pg279q listed. The XB270HU shows up at $699.99 too. These are real prices, with free shipping chucked in, and I could (and did) have the ability to actually buy at these prices.

I'm (tentatively) glad I scored at pg279q instead of the older XB270HU (which I wasn't even looking at anymore), given the price would have been the same, but I'd be fooling myself if I didn't remember that the differences between these panels is minor, as the newer panel is apparently just a minor revision of the older one. "Is the pg279q really $100 better than the xb270hu?" is simply the relevant question I'm suggesting people ask themselves. Likewise, is the peace of mind of a "new in box" pg279q really worth $100 more than an open box deal? Again, the same question. And likewise people might ask the same of these IPS monitors versus recent TN ones, or indeed of 144Hz versus 60fps, and so on. Most of us who decided on these monitors have already boxed ourselves in with wanting the best specifications across the board, but I see no reason to ignore the choices still available given that information.

In case anybody's keeping track, I rediscovered the monitor with dual refresh rate ranges: The Eizo Foris FS2735, which has "low" and "high" FreeSync ranges, allowing you to choose either 35-90Hz, or 56-144Hz. Obviously, people who are hovering around the 40-60Hz range aren't well served by these bifurcated ranges, but hopefully it'll be manageable for most. One also hopes it won't be an issue in the future, but on LCDs with FreeSync there will always need to be proper panel drive settings.

For OLED, though, I can't help but wonder if FreeSync is good enough.

[Guspaz]

Sorry, I forgot to put the ".ca" on "newegg", those are the Canadian prices. They are the actual prices to buy the monitor, although the ASUS is currently out of stock.

[Ed Oscuro]

Ah, once again I'm disheartened and disappointed in the tech tax my overseas (or, in this case, over-lake) brethren have to pay. But it goes back to what I was saying: Check out all the prices, make sure you're getting what you want out of it for any extra you pay.