LG 27GK750F-B - 240Hz, 27" 1ms Blur reduction, Freesync

[k2viper]

But have you tried even bigger vertical totals?

With 120Hz on a 240Hz monitor you should be able to support double size vertical total as 240Hz. So you should theoretically support VT2652 (double your VT1326) -- or VT2604 120Hz for a VT1302 240Hz -- essentially an exact double VT for half refresh rate. (assuming Horizontal Total is the same for both modes). Exact same Pixel Clock means you can exactly double your Vertical Total while halving your refresh rate (while maintaining same Horizontal Total). Or quadruple Vertical Total for one-quarter refresh rate.

Yes, sure, I tried it, the problem is if VT goes higher then 1586-1590 strobing just goes off, greys out in OSD, and OSD displays wrong current refresh rate (e.g. 157hz while its 144hz). So maximum VT working for me with strobing, was 1582-1586. I tried both 120 and 144hz, and the same maximum VT disables strobing. I experimented using Nvidia CP (there is "test" button which is usable when you want to immediately try, is the new VT working or not).

First things first, what's up with the word "faster" in brackets?
And then... what is 1ms motion blur reduction supposed to mean? 1ms persistence?
or 1ms response time...but only when strobed? that wouldn't make much sense...

"Faster" is a max OSD overdrive mode. Its absolutely usable, overshoot barely visible. 1ms blur reduction is a strobing, works 120-144-240hz only.

and to top it all off, they also state on the product page, that blur reduction can't be used together with Fresync and "DAS" with the latter being a complete mistery box, even after googling around...
The only information I could find about "DAS" is that it's supposed to reduce input lag... (similarly to Benq's instant mode, I assume, but don't quote me on that)
However, not being able to use instant mode when strobing, wouldn't make much sense either, now would it?

Freesync could not be enabled with blur reduction simultaneously, that's the common thing on every VRR monitor having strobed mode.
DAS - is advertised, but I havent seen this option in OSD, and other owners over the web havent found it too.
I think it may be available e.g. only on HDMI connection (i use Displayport), or its just not user switchable and "always on". Anyways, I dont feel any kind of input lag using this display. Its very responsive, not matter if I use blur reduction or not (speaking of 240hz). Basically in MBR mode it should have an additional ~1/2 frame of input lag, but at 240hz its only 4.1ms/2 = 2,05ms, I doubt that can be reliably felt by a person.

I think you're being WAY too harsh on your monitor.
The crosstalk at 120hz default is *MILES* better than any of the Benq monitors at 120hz without a VT tweak.

Perhaps I'm just used to strobing on my old ASUS VG278H lightboost 10%, which has the same form factor (27" 1080p), and its crosstalk at 120hz looked more faint then LG's one. You know, Nvidia does its own tricks to minimize crosstalk. But okay, lets count 120 and 144hz LG's modes fine too

[Gregix]

Just to not make mistake(in near future) IF I play game, said 120-350FPS range(weird game engine, CPU dependant), and I am on xl2720 atm, should I look up on this screen? I mean, bigger res does not attract me. I used to my Benq.
Will I see any improvement goin from 120Hz with BBR to 240Hz with LG blur reduction?
I mean, as I cannot have 240FPS constant, and I am not using any Vsync or so, will it be good or worse experience than now?

[Falkentyne]

But have you tried even bigger vertical totals?

With 120Hz on a 240Hz monitor you should be able to support double size vertical total as 240Hz. So you should theoretically support VT2652 (double your VT1326) -- or VT2604 120Hz for a VT1302 240Hz -- essentially an exact double VT for half refresh rate. (assuming Horizontal Total is the same for both modes). Exact same Pixel Clock means you can exactly double your Vertical Total while halving your refresh rate (while maintaining same Horizontal Total). Or quadruple Vertical Total for one-quarter refresh rate.

Yes, sure, I tried it, the problem is if VT goes higher then 1586-1590 strobing just goes off, greys out in OSD, and OSD displays wrong current refresh rate (e.g. 157hz while its 144hz). So maximum VT working for me with strobing, was 1582-1586. I tried both 120 and 144hz, and the same maximum VT disables strobing. I experimented using Nvidia CP (there is "test" button which is usable when you want to immediately try, is the new VT working or not).

First things first, what's up with the word "faster" in brackets?
And then... what is 1ms motion blur reduction supposed to mean? 1ms persistence?
or 1ms response time...but only when strobed? that wouldn't make much sense...

"Faster" is a max OSD overdrive mode. Its absolutely usable, overshoot barely visible. 1ms blur reduction is a strobing, works 120-144-240hz only.

and to top it all off, they also state on the product page, that blur reduction can't be used together with Fresync and "DAS" with the latter being a complete mistery box, even after googling around...
The only information I could find about "DAS" is that it's supposed to reduce input lag... (similarly to Benq's instant mode, I assume, but don't quote me on that)
However, not being able to use instant mode when strobing, wouldn't make much sense either, now would it?

Freesync could not be enabled with blur reduction simultaneously, that's the common thing on every VRR monitor having strobed mode.
DAS - is advertised, but I havent seen this option in OSD, and other owners over the web havent found it too.
I think it may be available e.g. only on HDMI connection (i use Displayport), or its just not user switchable and "always on". Anyways, I dont feel any kind of input lag using this display. Its very responsive, not matter if I use blur reduction or not (speaking of 240hz). Basically in MBR mode it should have an additional ~1/2 frame of input lag, but at 240hz its only 4.1ms/2 = 2,05ms, I doubt that can be reliably felt by a person.

I think you're being WAY too harsh on your monitor.
The crosstalk at 120hz default is *MILES* better than any of the Benq monitors at 120hz without a VT tweak.

Perhaps I'm just used to strobing on my old ASUS VG278H lightboost 10%, which has the same form factor (27" 1080p), and its crosstalk at 120hz looked more faint then LG's one. You know, Nvidia does its own tricks to minimize crosstalk. But okay, lets count 120 and 144hz LG's modes fine too

No you are correct. The Asus uses a form of accelerated scanout through the LC panel, which allows for maximum strobe signal timing, making crosstalk as low as possible. The Benq XL2411Z, XL2420Z and XL2720Z, I found out actually uses a reverse engineered form of Lightboost, because the original T series models had the same scaler and used Lightboost as well. The way Benq interfaced the scaler with blur reduction, allowed you to use an increased vertical total to get the exact same effect as Lightboost did, by using the VT range of 1497-1502. This range is significant, because everything from VT 1486-VT 1496 gives a black screen and out of range error, VT 1481-VT 1485 show a display but still gives an out of range error, and everything from VT 1410 to 1480 is black screen OOR. What is noteworthy is the SCALER internal resolution that is reported via the "Factory" menu. With a VT of 1481-1485, despite the OOR error, the internal scaler resolution is "1920x1440". This resolution is not supported and out of bounds. However with a VT of 1497-1502, it is "1280x1440". This was clearly done intentionally (because of Lightboost support), and this lower HT means you don't get an out of range error. What's funny is, with a VT of 1400, you do get an out of range error and the internal resolution shows as 1792x1344.

The Benq monitors, thus have the exact same crosstalk amount as Lightboost mode, provided the strobe timings are set to strobe phase 000 (1 frame ahead=1 frame input lag) and strobe duty 009 (100hz=1.5ms of persistence, equal to Lightboost 10%), etc.

For the 27" monitors, since unlike 1920x1080, where the default VT is 1138 for 100hz (I think), the Benq XL2735 has a default VT of 1525 at 2560x1440, and allows the maximum VT of 1849 to be used at 100hz and 120hz (might require reducing the HT, otherwise VT 1825 works), for the same crosstalk reduction.

In your case, a VT of 1580 is a very tiny reduction in crosstalk, and strobing not working if you go higher is clearly a firmware limitation. You can contact LG about it, but good luck finding someone who understands you. You would have to be transferred to their actual engineering department, which may be an overseas contact via email.

[k2viper]

In your case, a VT of 1580 is a very tiny reduction in crosstalk, and strobing not working if you go higher is clearly a firmware limitation.

You think at VT ~1600 there is "black window" as you described for Benqs, and I should keep looking for bigger VT's?
Curious if I'll find higher VT for 240hz... Tried all the way up to 1580 @ 240hz - black screen.

[Chief Blur Buster]

I took some pictures, but I think you dont want to look at standard package and display body pics, but crosstalk shots I took look very smeared, I need to try different camera or camera settings.

You thought wrong!
I would like to look at those photos!

He already took pictures in a newer reply:
viewtopic.php?f=2&t=3823&p=31030#p31012

Strobe crosstalk photography is an exception where it doesn't need to be pursuited to be relatively close to WYSIWYG -- as long as the camera is configured to capture only one strobe flash. The (different) goal is to inspect the crosstalk, rather than the motion blur (persistence). Crosstalk is visible in both static (one flash) and pursuited (stacked refresh cycles), and static photography is easier for crosstalk photography.

[Chief Blur Buster]

First things first, what's up with the word "faster" in brackets?
And then... what is 1ms motion blur reduction supposed to mean? 1ms persistence?
or 1ms response time...but only when strobed? that wouldn't make much sense...

Probably.
MPRT (persistence) is not the same thing as GtG.

There are monitors with 16.7ms MPRT but 1ms GtG (sample-and-hold)
And monitors with 1ms MPRT but 5ms GtG (strobed, because GtG is hidden by darkness).

For an explanation of the two different response-time measurement methods, please see:
1. High Speed Video of LightBoost -- www.blurbusters.com/lightboost/video
2. Blur Busters Law: Amazing Journey To Future 1000Hz Monitors -- www.blurbusters.com/1000hz-journey

Pixel Response: MPRT Not Same as GtG

These are two very different pixel response measurements. There are many 60Hz displays with <1ms GtG (e.g. OLED) but has 16.7ms MPRT (lots of motion blur).

GtG is pixel transition time. GtG stands for Grey-To-Grey.
MPRT is pixel visibility time. MPRT stands for Moving Picture Response Time

Persistence (in milliseconds) is also known scientifically as “MPRT” in research papers (Google Scholar search). Quoted as a number, MPRT and persistence mean the same thing by modern virtual reality scientists and newer display engineers. For example, Chief Scientist at Oculus, Michael Abrash, wrote a famous blog article that use the “persistence” terminology.

Cheers,

[A Solid lad]

"Faster" is a max OSD overdrive mode. Its absolutely usable, overshoot barely visible.

Just as I expected, thanks for clearing that up.

1ms blur reduction is a strobing, works 120-144-240hz only.

This, however clears up nothing... I'm well aware it's strobing.
I thought that it was apparent from my wording: "1ms response time...but only when strobed?"

What made no sense to me, is how they basically state that their monitor has a response time of 1ms when strobed, but 2ms non-strobed... (ikr, they are probably mixing up persistence and gtg response time here, that's why I'd like someone to clear it up)

Freesync could not be enabled with blur reduction simultaneously, that's the common thing on every VRR monitor having strobed mode.

Again, you told me something I already knew, I have no idea why you thought I didn't...
Anyway, the thing that was puzzling for me was, why they won't let you use DAS (A feature I assume to be very similar to benq's "instant mode"...this still needs verification though) while strobing...
I found posts on the web claiming that DAS is not always on... in some cases, it's greyed out, whie displaying "off", other times greyed out while saying "on"... it's puzzling.

He already took pictures in a newer reply:
viewtopic.php?f=2&t=3823&p=31030#p31012

Yes I saw those... I meant that I'd be curious to see those "standard package and display body pics" that he thought nobody would care about.
That's why I wrote "You thought wrong!".

Probably.
MPRT (persistence) is not the same thing as GtG.

There are monitors with 16.7ms MPRT but 1ms GtG (sample-and-hold)
And monitors with 1ms MPRT but 5ms GtG (strobed, because GtG is hidden by darkness).

For an explanation of the two different response-time measurement methods, please see:
1. High Speed Video of LightBoost -- http://www.blurbusters.com/lightboost/video
2. Blur Busters Law: Amazing Journey To Future 1000Hz Monitors -- http://www.blurbusters.com/1000hz-journey

I know the difference between the two, I just don't know what LG is claiming here.
You're saying it's probably persistence?

[dogroll]

I bought an 8350K to replace my 2500K, currently have it overclocked to 4800 (waiting on liquid metal and delid to get 5.2--5.3). Still not enough to run TF2 pubs at solid 240Hz, but it does allow solid 144Hz, which means 144Hz strobed becomes an option. Really can't decide whether I prefer strobed 144Hz or 240Hz with freesync. 144Hz definitely looks choppier than 240Hz. Surprisingly I don't find the strobing such a competitive advantage as I did before, when I went from a 75Hz strobed monitor to a 144Hz non-strobed, and hated the motion blur at 144Hz non-strobed.

[k2viper]

This, however clears up nothing... I'm well aware it's strobing.
I thought that it was apparent from my wording: "1ms response time...but only when strobed?"

I think that's just a marketing name for the blur reduction feature. "1ms", "2ms" actually shows 3,6ms avg GTG according to hardware.info tests.

Anyway, the thing that was puzzling for me was, why they won't let you use DAS (A feature I assume to be very similar to benq's "instant mode"...this still needs verification though) while strobing...
I found posts on the web claiming that DAS is not always on... in some cases, it's greyed out, whie displaying "off", other times greyed out while saying "on"... it's puzzling.

Yes, that's still unclear to me. Posts claiming that DAS is greyed out in some cases, probably refers to other LGs monitor models, I also googled it, there's also some other LGs monitor models with advertised DAS, but no such option in OSD. We're not the ones confusing about it

Surprisingly I don't find the strobing such a competitive advantage as I did before, when I went from a 75Hz strobed monitor to a 144Hz non-strobed, and hated the motion blur at 144Hz non-strobed.

Same here. Simply 240hz nonstrobed is really good on this monitor, and even 144hz nonstrobed is good, thats why strobing isnt a must on it. Strobing still makes some things easier, e.g. I play Overwatch heroes with tracking aiming as soldier76 or zarya, and strobing really help to focus on tracked targets, making their edges clearer and more natural. But there are many more general scenarios where strobing dont make sense. I'm also fine with slightly lower brightness of strobing, but some people are not.
Anyway, having this feature as good as it is, makes us have choice. Many other models have strobing only at 144 or does not have it at all, so there's even more tradeoffs then we have.

[k2viper]

Pics of the body, box, accessories can be seen e.g. here: http://m.post.naver.com/viewer/postView ... o=11981539

I confirm that my monitor has the same build, package, and accessory contents
There's many others user reviews, on Korean but pictures are in.

Response time measured: numbers looks good


Input lag (SMTT 2.0) measured as low as 2-4ms which is very good, I think.