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

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

Postby yehaw » 01 Dec 2018, 12:49

Pretty funny, but for some reason, when I got my monitor, it didn't auto-detect properly. I had to manually set the resolution to native and set 240hz. After that, I had a system update scheduled to restart. After restarting, apparently NVCP was reset to 144hz. So the reason why it felt laggy, was because my refresh rate was reset to 144hz. :lol:

As far as fixing the weird stutter I see, I tried the CRU settings detailed and then using the restart file, but it just loses signal after I apply it? I had to round up the refresh rate, as mentioned in the guide. I restart my PC and it gets back into windows and displays picture. If I go back to CRU, it shows the value of 239.760hz that I changed to, but I'm unsure if it's actually applied or not? I can still see a weird judder panning back and forth in games. It almost looks like a FPS hiccup, but my FPS is stable 300+. Image of settings I tried.

And can anyone else that owns this monitor confirm if there is a hissing coming from the circular vents on the back? I'm not sure if I'm sensitive to the frequency of this sound, but it's been driving me mad, as I have a near silent PC. I tried different power plugs and strips, tried messing around with brightness, but can't get this dam noise to go away.

Other than these issues, I'm really impressed with it. The coating is very acceptable, text and images look sharp, the colors have some pop, and my favorite thing - great uniformity and probably the best backlight I've ever owned, as it's the least amount of bleed I've ever seen for any monitor. The stand is also very nice, I just wish it went a bit lower.
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Re: LG 27GK750F-B - 240Hz, 27" 1ms Blur reduction, Freesync

Postby k2viper » 01 Dec 2018, 13:15

If CRU is displaying 239,760 you successfully applied the fix. As I see on the screenshot, settings are correct.
The known juddering/stuttering if refreshrate is not exact 239,760 is occuring once/0,5sec - once/1sec, if you're getting lower judder rate, probably I havent seen that kind of issue.
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Re: LG 27GK750F-B - 240Hz, 27" 1ms Blur reduction, Freesync

Postby yehaw » 01 Dec 2018, 18:41

k2viper wrote:If CRU is displaying 239,760 you successfully applied the fix. As I see on the screenshot, settings are correct.
The known juddering/stuttering if refreshrate is not exact 239,760 is occuring once/0,5sec - once/1sec, if you're getting lower judder rate, probably I havent seen that kind of issue.


I think it might have been PC stutter, W10 is an absolute mess lately for me, just problem after problem with BS forced updated policy. Did a fresh install and seems to be butter smooth with 239.760 now.

Also worth to note, after some research, the issue with artifacts might be related to an NVIDIA driver issue:

"Display corruption may occur on higher refresh rate DisplayPort monitors upon resume from sleep mode"

I always use sleep, so likely have to wait for a driver fix on that issue.

Is it worth exchanging to fix the coil whine/high frequency sound I hear from the back, or do others experience the same issue? Don't want to waste my time exchanging if they all have the same problem.
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Re: LG 27GK750F-B - 240Hz, 27" 1ms Blur reduction, Freesync

Postby k2viper » 02 Dec 2018, 09:55

I dont hear any coil whine on my unit.
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Re: LG 27GK750F-B - 240Hz, 27" 1ms Blur reduction, Freesync

Postby daniloberserk » 02 Dec 2018, 18:21

k2viper wrote:daniloberserk, where your 240hz option disappears when you apply vt1304? It should stay in place in windows screen properties. If it's not it may worth trying to apply it via AMD driver custom resolution panel. If still no luck, it may be some AMD graphics driver flaw. I've heard no reported issues with applying this trick on Nvidia GPUs.

yehaw, TFTCentral measured it in 1:1 and Full wide aspect modes (I directly asked them via email), but after all a forum user found and tested, that only Original scaling mode has lowest lag, it is one full frame lower then both Full wide and 1:1. I added it in TLDR post, make sure you use Original aspect mode. You also complain about stuttering/juddering, it has a solution. Read TLDR post in thread start.
Still, no any green or other colored artifacts on my unit, also no any coil whine. It is possible that your unit is defective.


Yep, it disappears from the windows options, I'll try with the AMD driver.

Edit: No luck with the AMD driver also, it just displays an error saying that the changes is not compatible with the display.
Edit2: Tried a few vtricks, it seems my higher value is something about 1192, with this value the monitor stops being detected as a lg 750 in my windows, and still stutters a lot. As soon as I drop to vtotal 1182, seems completely fixed on testufo.com, very weird.

I'm on ver 3.07
Last edited by daniloberserk on 03 Dec 2018, 04:38, edited 2 times in total.
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Re: LG 27GK750F-B - 240Hz, 27" 1ms Blur reduction, Freesync

Postby daniloberserk » 02 Dec 2018, 18:24

k2viper wrote:
daniloberserk wrote:k guys, I don't know how "precise" this tests I made is but I hope it can help for something.
I have a Sony Xperia XZ premium, which can record 960fps for about 1/4sec. I made some comparisons with the LG 27GK750F and my Benq XL2420z

144 Hz on both displays, aspect: full wide on LG:
https://www.youtube.com/watch?v=zrCryMk ... e=youtu.be

144Hz on both displays, aspect: original on LG:
https://www.youtube.com/watch?v=MG_QGNM ... e=youtu.be

240Hz vs 144Hz, aspect: original on LG:
https://www.youtube.com/watch?v=vVgINau ... e=youtu.be

The Benq is connected via DVI-DL and the LG on d-port on my R9 390x.

I'm note sure how "precise" this test is but it seems the LG is slight slower on 144Hz, but faster on 240Hz. Fullwide x Original seems about the same for me...

Edit:

Two more tests...

Full Wide - 240Hz: https://www.youtube.com/watch?v=Dav8tR5 ... e=youtu.be
Original - 240Hz: https://www.youtube.com/watch?v=rC2oojz ... e=youtu.be

Again... I don't know if this can help or something... It seems strange, sometimes the LG is faster and other times, the Benq is faster?


Well, some notes on measuring technique:
Display cloning dont work well for this purpose, a clone source display should have about a frame less delay then cloned one. Use display panning.
Any browser based stopwatch timers are innacurate due to Vsync is forced in Windows and broswer. That's why browser-based measured results are always multiple to given frame time. It is innacurate but still can give an idea which mode is faster and which is slower.
You show in OSD that freesync is active. Disable it for display lag measuring purpose.


Nice, interesting notes there! Do u know any software who make this easier to test? Also, maybe isn't better for the chief to make a standalone software with the tests of testufo.com ? Since the browsers always have issues here and there...

Edit: So, after reading some posts from the Chief, the article gsync 101, etc... I came to a conclusion there's no way I can made tests precise enough. But I'll do some more tests anyway since they can provide at least some margin of error about the displays.
Seems that D-Port have more lag then DVI... I'm quite shocked honestly. This is a incredible hot topic with tons of info, it seems the Chief is working for a substitute to the SMTT 2.0, which is great... As soon as I can I'll post some more videos. This time with freesync off and panning videos (still browser tests though since I don't have a clue of how can I test effectivelly). So I just got this video: https://www.youtube.com/watch?v=e8ZtPSIfWPc and set to 2x timespeed. Panned the two screens, put the video in the middle and recorded.

Here are the tests:
144Hz
https://youtu.be/ETVDT7O5sH0
https://youtu.be/ZzzFpkRmhBY
https://youtu.be/UzIqwKSuIFs

240Hz
https://youtu.be/3v7kZWMdJU4
https://youtu.be/o1UQiYQsji0
https://youtu.be/wnS1KIXiwKU
https://youtu.be/0jLEE6olv-8

So, my conclusion (at least from this tests):

On 144Hz, the Benq is ALWAYS faster.
On 240Hz, the LG is faster EXCEPT on 1:1 Aspect Ratio mode.

Fullwide and Original seems to be about the same.

Not sure if this lag happens because of the display, or the cable, or whatever. Benq is on DVI-DL, LG on D-Port.

So, if you're planning to use freesync on high competitive gaming with low FPS, it seems not a great deal (still, much faster then the average display).

240Hz seems always great comparing to 144Hz. I'm not sure what people say about the "lag feeling", played as Ashe only on OW on one of my accounts since I got this display and the results are impressive: https://www.overbuff.com/players/pc/dou ... ompetitive got almost 20k of heroscore being a Diamond pleb, which scores me at the top 4% on Overbuff, played a bit with freesync and the majority of the time with MBR off and 240Hz (fps uncapped). Even on this conditions (at least for me), I can feel a difference between 240Hz and 144Hz, to bad my setup can't hold 200FPS + all the time, so I'm not sure where is my threshold, but feels incredible snappy and smooth to track targets, so that's my anecdotal evidence regarding my feeling about the display.
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Re: LG 27GK750F-B - 240Hz, 27" 1ms Blur reduction, Freesync

Postby Kheri » 03 Dec 2018, 04:48

dogroll wrote:Simply put the monitor in 240Hz regular mode (freesync or not, just MBR disabled), then switch it to MBR via the OSD, and the stutter will occur. Not always, and just now trying to reproduce it I had to try about 7 times to get the 'bug' to happen, but before it was happening very often.

I took a crappy video on my phone to show the stutter: https://streamable.com/kwd8v


Yes, this happens sometimes (at least after using CRU). this is why I recommended yehaw switch between the two modes.
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Re: LG 27GK750F-B - 240Hz, 27" 1ms Blur reduction, Freesync

Postby Kheri » 03 Dec 2018, 05:16

k2viper, wondering if you'd be willing to help me out, I can see in your strobe crosstalk pics you have one maybe two duplicated images at the center line, right? Is that reflective of reality or how your eyes see it? On mine, I can see 2 of the crosstalk images clearly, and a very faint third one. It actually makes the street names in the panning test quite difficult to read.

I think it might be a good idea to put the crosstalk pics in the first post, sort of as a way to show the results.
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Re: LG 27GK750F-B - 240Hz, 27" 1ms Blur reduction, Freesync

Postby k2viper » 03 Dec 2018, 09:01

daniloberserk, thanks for your efforts. As you may already got, this 60fps youtube video is barely useful for measuring such high refresh rate displays like 144/240hz. I am not sure, that even being set at 2x timespeed, youtube (flash/html5) player plays it with actual 120 frames per second and not dropping frames, even if I set your videos to 0,25 and watch these slow-mo sections there are some dropped/skipped 60fps video frames seen, I think it's a youtube player flaw, not your technique.

But still, we can have an idea which modes are faster. Your Benq is in Instant mode, right? I dont think DVI-D is superior to Displayport in terms of input lag, but I suppose that 144hz mode is not somewhat "native" for many of 240hz displays and their scalers/panel electrionics drivers.

1:1 seems to be clearly the slowest mode. 144hz Benq is often a frame ahead of 1:1 LG.

Original is fastest, in Original you more often can catch a 16ms higher frame number on the left (LG) screen, there are even some double frames ahead stopwatches I found.

I dont know other then SMTT 2.0 tools that would not be browser based, though.
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Re: LG 27GK750F-B - 240Hz, 27" 1ms Blur reduction, Freesync

Postby k2viper » 03 Dec 2018, 09:09

Kheri wrote:k2viper, wondering if you'd be willing to help me out, I can see in your strobe crosstalk pics you have one maybe two duplicated images at the center line, right? Is that reflective of reality or how your eyes see it? On mine, I can see 2 of the crosstalk images clearly, and a very faint third one. It actually makes the street names in the panning test quite difficult to read.

I think it might be a good idea to put the crosstalk pics in the first post, sort of as a way to show the results.


I can read street names without much effort, I may just be used to strobing since I was on full-time Lightboost from 2012.
These are the most accurate photos I have to reproduce what an eye is actually seeing in testufo.com/crosstalk test - photos made with hand pursuit :)

ImageImage

At center, crosstalk is very faint.
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