XL2720Z -> XL2746S Upgrade

Adjusting BENQ Blur Reduction and DyAc (Dynamic Acceleration) including Blur Busters Strobe Utility. Supports most BenQ/Zowie Z-Series monitors (XL2411, XL2420, XL2720, XL2735, XL2540, XL2546)
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Chief Blur Buster
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XL2720Z -> XL2746S Upgrade

Post by Chief Blur Buster » 13 Mar 2021, 19:38

Hello Falkentyne,
Falkentyne wrote:
13 Mar 2021, 18:35
Got my XL2746S today from Amazon. Never ordered a monitor on amazon before, it was always Newegg. And I know about all the horror stories of dead pixels and IPS lotteries and eventually people getting "banned" from Amazon so I was worried.

Anyway looks like I "won" the panel lottery. Can't find any dead pixels. Panel seems as flawless as my XL2720Z (so far).

Messed around in the Service Menu
DyAC High and Premium seem to just have a different brightness? I did notice that when changing one, the strobe phase and strobe duty (Area and intensity) seem to reset to a saved value, there seems to be a value saved for each setting.

Monitor seems to have the "VT 1500" tweak built in (aka accelerated scanout), just like Lightboost mode. Strobe crosstalk at 100hz and 120hz are literally identical to the XL2720Z with a 1500 tweak (I compared it pixel by pixel), so no 100hz/120hz VT Tweak is even needed, with the exception that you can't shut off the backlight by raising the Area too high (to where it clips into the persistence range). Raising the Area to 100 doesn't quite drop the crosstalk field to the very bottom (I assume that's' because on the XL2720Z/XL2420Z etc, increasing the Strobe Phase when a VT tweak is active limits the maximum strobe duty, e.g. Phase 049 on XL2720Z with VT Tweak limits max duty to 001 (dimmest). So most likely, being able to lower the crosstalk field lower than the position Benq allows at "100" Area would limit Intensity to values higher than 1, and that would be a customer service nightmare, so i can see why that's capped there.
You do eliminate 1 advantage of large vertical totals, but you still have another advantage:

Vertical Total tweaks still reduce input lag via the Quick Frame Transport effect. Large Vertical Totals force the visible part of the refresh cycle to be transmitted faster over the DisplayPort cable, so it can be refreshed sooner, so that the strobe backlight can flash sooner.

For example, VT1500 means the refresh cycle is delivered in only 1080/1500ths of a refresh cycle (of the current Hz). If you're using VT2250 (which works on the XL2746S at 120Hz), you reduce DyAc strobe lag by up to about 4 milliseconds.

There are multiple benefits of large Vertical Totals, even if the monitor is scan-converting. The problem with automatic large vertical totals in the monitor is that it has to buffer VT1125 to do internal VT1500 or something like that on the panel (see diagrams, so you can avoid this buffering behavior by making sure your external VT is at least as big as the internal VT -- even if there's no crosstalk quality differences.

(This is what 240 Hz BenQs do by default for low-Hz modes like 60 Hz or 120 Hz)
Image

(This is what you can get your 240 Hz BenQ to do)
Image

With large VT's, more refresh cycle is transmitted more quickly sooner on the cable, before being refreshed onto the panel,
Falkentyne wrote:
13 Mar 2021, 18:35
Possibly a VT tweak may allow crosstalk to be lowered more than the default value (e.g. each point of Area may lower the crosstalk more pixels than the "default") but I haven't tested this yet. I was only doing a "dry run" on my laptop's mini DP port to check for dead pixels.

OD Gain is funny.
It goes up and down by values of 1, in hexadecimal. You can adjust exactly how much ghosting "amount" you want, although it cant be removed fully. You can turn the UFO ghosts totally completely purple if you want. OD Gain=00 is like overdrive is disabled.

I doubt I can hack 60hz single strobe on this. (e.g. by tricking the monitor into thinking it's running at a higher refresh rate). I tried it on my XL2720Z and it still double strobed at 85hz and lower. I'll try a custom resolution made for 120hz and try lowering the refresh rate without changing the other timings but I think the monitor is too smart for me. Not doing this now. Maybe later.
The easiest way to create a Quick Frame Transport mode is this one:
Chief Blur Buster wrote: Optional ~4ms reduction in strobe latency for 120Hz strobe on 240Hz monitors

There's up to a 4ms strobe latency savings if you decide to hit two birds with one stone.

<Optional Advanced User Tweak: Quick Frame Transport>

Geometrically, the pixels are delivered left-to-right, top-to-bottom over a cable from GPU to monitor -- in this order in this pixel layout for all screens, per refresh cycle.

Image

Like reading a book or a calendar, pixels are delivered one at a time over a video cable (VGA, HDMI, DVI, DisplayPort) at the pixel clock speed. The porches/sync intervals are spacers between pixel rows and between refresh cycles.

So this diagram is repeated 120 times on the cable for 120 Hz refresh cycles -- in the art of delivering 2D pictures over a 1D wire.

But How Do We Deliver a 100Hz or 120Hz Refresh Cycle In 1/240 second?

There are ways to speed up delivery of individual refresh cycles over a video cable requires a large blanking interval (vertical sync/porches), which can compress the transmission of the active visible refresh cycles to a shorter time period (e.g. 100Hz refresh cycle transmitted over DisplayPort in 1/240sec).

This helps strobing lag a bit because pixels can be delivered faster, and refreshed onto the panel sooner, to allow the strobe backlight to flash a bit sooner -- up to about 4ms sooner (for 120Hz 8ms refresh cycles delivered in 1/240sec 4ms delivery)

The most applicable FAQs are Custom Resolution Utility glossary, as well as Quick Frame Transport.

The most common 120Hz QFT timings is as follows:

Image

From Advanced XG270 Tweaks.
This reduces PureXP latency by about 4ms at 120Hz.

Math Calculation For Other Refresh Rates
Most 1080p signals use a typical Vertical Total 1125 (1080 visible rows + 45 spacer between refresh cycles as blanking interval). After putting the radio button on the "Total" you can usually calculate your ideal QFT VT by multiplying 1125 by 240 then dividing by your preferred refresh rate. At 100 Hz, you can use (1125 * 240 / 100) = VT2700 at 100Hz. Just keep all 240 Hz ToastyX numbers unchanged when changing vertical total and refresh rate (the only two numbers that should change). Make sure horizontal refresh rate is exactly unchanged and make sure pixel clock (dot clock) is exactly unchanged, versus the original working 240 Hz mode.
1. Start with a working default max-Hz mode
2. Put radio button on "Vertical"
3. Put radio button on "Pixel Clock"
4. Don't edit any other number except "Vertical Total". Increase Vertical Total and you'll see Hz automatically decrease.
5. Now you have a large-VT low-Hz mode derived from your working max-Hz mode.

More advanced information can be found at Quick Frame Transport thread.

</Optional Advanced User Tweak: Quick Frame Transport>
Head of Blur Busters - BlurBusters.com | TestUFO.com | Follow @BlurBusters on Twitter

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Falkentyne
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Joined: 26 Mar 2014, 07:23

Re: XL2720Z -> XL2746S Upgrade

Post by Falkentyne » 13 Mar 2021, 20:06

Thank you Chief! This is some juicy information. A lot of this stuff is confusing and definitely takes some time to sink in but it makes sense.

Falkentyne
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Re: XL2720Z -> XL2746S Upgrade

Post by Falkentyne » 13 Mar 2021, 20:52

Chief, Single Strobe cutoff is around 96hz (just like in XL2720Z).

85hz and 75hz both double strobe. It just looks alot better at 85hz than it does at 60hz but it's still a double.

*Edit*

VT 1350 works at 120hz.
So 100hz double strobes at VT 1500, 1350 and 1250. Single strobes at stock and VT=1200. hmm...interesting.

Weird.

Tried multiple VT's so far. I could not trick 60hz into single strobing at all. I figured if I could make 100hz double strobe, maybe there is a way to make 60hz single strobe. But no luck...

The panel is a true 8 bit panel (no FRC).
https://www.displayspecifications.com/en/model/e9fd1c78

nheira0000
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Joined: 28 Feb 2021, 23:16

Re: XL2720Z -> XL2746S Upgrade

Post by nheira0000 » 17 Mar 2021, 03:03

I just want to know about the advantages it brings to the game fps?

Falkentyne
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Joined: 26 Mar 2014, 07:23

Re: XL2720Z -> XL2746S Upgrade

Post by Falkentyne » 17 Mar 2021, 12:37

Some more stuff on this monitor.

1) forget about doing anything to make single strobe below 99hz work. It just doesn't work. Period.
2) While the default VT (vertical total, via custom resolution) at stock 100hz matches the crosstalk that an XL2720Z has at VT 1500, for some reason, changing the VT higher than 1200 makes the monitor *double strobe*. VT 1350 and VT 1500 double strobe. VT 1200 has a slight crosstalk reduction over the default VT 1133. However the monitor will single strobe again if you use a very large VT.

I found these work great for 100hz and 120hz and remove *ALL* of the Crosstalk. ALL of it. Just set "Area" to 0 in the service menu so there's none at the top of the screen:

1920 x 1080 @ 100hz
Porch: 88,4 (48,3 may or may not work, didnt test)
Sync: 44,5 (32,5 may or may not work, didn't test)
Horizontal Total: 2200 (2080, along with 48,3 and 32,5 may or may not work, didn't test).
Vertical Total: 2250.

Do the same for 120hz.

Both of these have absolutely ZERO crosstalk and you will love it.

For 144hz, try this: *Edited*
porch: 48,3
Sync: 32,5
HT: 2080
VT: 1650

Works great.

For 165hz it gets a bit more iffy with the monitor being slow to accept a signal if you go higher than 1420 VT:
But you can try:
Porch: 48,3
sync: 32,5
HT: 2080
VT: 1474 (if this gets annoying try VT 1420 but the crosstalk will be a small bit higher).
You can also try HT: 2001, VT 1470 with Porch 24,3 and Sync: 32,5.
It's hard to get fast mode switching into 165hz if the VT Is higher than 1420. VT's higher than 1490 either take up to 20 seconds or even longer.

for 182hz, use the same values, but VT: 1350 this time. (EDIT: VT 1500 works at 182hz and at 180hz. Something is REALLY screwy about the refresh rate range from 155hz to 179hz with VTs!!!)

The default 240hz value is bad. Causes some "very" strange frame skipping. I'm not sure if it's the Nvidia driver or the monitor at fault here.

Change it to these values:
Front porch: 24,3
Sync width: 32,5
HT: 2001
VT: 1240
Last edited by Falkentyne on 18 Mar 2021, 14:07, edited 2 times in total.

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Chief Blur Buster
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Re: XL2720Z -> XL2746S Upgrade

Post by Chief Blur Buster » 18 Mar 2021, 13:37

nheira0000 wrote:
17 Mar 2021, 03:03
I just want to know about the advantages it brings to the game fps?
Motion blur reduction (strobing) doesn't help frame rate, but it improves the appearance of low frame rates.

For example, watch www.testufo.com with DyAC turned on. Observe how the first UFO is clearer, the second UFO has double images, and the third UFO has quadruple images.

Strobing is good for motion clarity of your framerate-matching-refreshrate games, and sometimes it's favourable to lower your frame rate & refresh rate in order to match strobe rate -- since GPUs can't always keep up to 240fps.
Head of Blur Busters - BlurBusters.com | TestUFO.com | Follow @BlurBusters on Twitter

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Forum Rules wrote:  1. Rule #1: Be Nice. This is published forum rule #1. Even To Newbies & People You Disagree With!
  2. Please report rule violations If you see a post that violates forum rules, then report the post.
  3. ALWAYS respect indie testers here. See how indies are bootstrapping Blur Busters research!

Falkentyne
Posts: 2793
Joined: 26 Mar 2014, 07:23

Re: XL2720Z -> XL2746S Upgrade

Post by Falkentyne » 18 Mar 2021, 14:01

Chief Blur Buster wrote:
18 Mar 2021, 13:37
nheira0000 wrote:
17 Mar 2021, 03:03
I just want to know about the advantages it brings to the game fps?
Motion blur reduction (strobing) doesn't help frame rate, but it improves the appearance of low frame rates.

For example, watch www.testufo.com with DyAC turned on. Observe how the first UFO is clearer, the second UFO has double images, and the third UFO has quadruple images.

Strobing is good for motion clarity of your framerate-matching-refreshrate games, and sometimes it's favourable to lower your frame rate & refresh rate in order to match strobe rate -- since GPUs can't always keep up to 240fps.
Yes this FPS=HZ is a problem when trying to play new games. No way you're going to maintain 240hz/240 FPS in any new game that isn't some indie FPS at 1080p, even on a RTX 3090. (and if you have a RTX 3090 you're going to crank up the details aren't you?). 144hz/144 FPS is much easier and 165hz/165 fps is a realistic target in games that aren't overloaded with ray-tracing. If you want to play at 240hz or, on a monitor that supports it, 360hz, it's just best that you disable blur reduction and just turn on Freesync or Gsync. A lot more enjoyable that way.

One of the nice things about the XL2746S is it can strobe with low crosstalk (and ZERO crosstalk at 100hz, 120hz and 144hz)

Just look at this. This is 144hz with VT 1650. Area is set to 0, Intensity set to 20 (dimmest is 25), and DyAc Premium at 80 Brightness.
ignore the dark bars.

https://i.imgur.com/3PgHcdc.jpg

This is REALLY fricking good.

Falkentyne
Posts: 2793
Joined: 26 Mar 2014, 07:23

Re: XL2720Z -> XL2746S Upgrade

Post by Falkentyne » 23 Mar 2021, 14:17

Some stuff I noticed.

Freesync (AMD card) doesn't work over directly HDMI 2 (at least on a HDMI 1.4 AMD r9 290X card, no idea about Vega or newer).

Freesync (AMD card) does work over HDMI 1 on a R9 290X, even though the monitor says "HDMI 2.0 only"

Freesync (AMD card) doesn't work over HDMI on either port if the Factory Menu is unlocked. It does work over displayport. Apparently the factory menu allows monitoring of the VRR mode and if VRR is enabled or not. But this doesn't seem to play nice over HDMI.

If the monitor is plugged in and the factory menu is unlocked on an AMD card over HDMI 2, trying to manually edit in freesync range in ToastyX CRU makes the AMD driver accept freesync even though the monitor OSD says it's greyed out. Starting a game at this point will cause a black screen/flicker off if the factory menu is unlocked.

Disabling the factory menu makes Freesync work over HDMI 2 without black screening. But you still can't enable it in the monitor if it isn't enabled beforehand--it's still greyed out. This seems to be a bug. If freesync is unlocked beforehand, then you can use it. Use HDMI 1, even though CRU will list refresh rates not supported on a HDMI 1.4 port, the AMD driver won't allow them but will still work at 120hz with freesync.

Trying to be cute and editing in freesync ranges over HDMI with DyAc enabled won't give you adaptive DyAc :) Unfortunately Masterotaku's Adaptive Sync+ULMB type mode just won't work. You lose.

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