Acer 390Hz monitor - XV252QF

[lyrill]

so guys, what's the significance of some minecrafter running 4 NVIDIA Tesla A100s with this monitor? bilibili BV1aP4y157Hk

[axaro1]

I got some better ufotests to compare the XV252QF at 390hz with VRB ON OD Normal vs Extreme.



Personally I've been sticking to OD Extreme. OD Normal is okay, not a huge difference between the two if you ask me except for dark transitions where OD Extreme seems like the better perfomer overall.

Also OD Extreme is yet another case of IPS panels with overshoot scaling decreasing with Black Equalizers/lower gammas, so it can be manipulated to have less overshoot with some minor Black Boost tweaks (that I'd do anyway considering the benefit that comes with black equalizing for competitive gaming in general), you don't only reduce the amount of overshoot but you also decrease the amount of transitions that generate it.

Strobing can also mitigate overshoot, just like in the case of the VG259QM and XL2546K, having an off duty cycle during peak overshoot will show less aggressive artifact behaviour.

[axaro1]

By the way, tweaking VT was more difficult than expected, CRU surprisingly gave me no infos regarding 390hz timings, every single attempt to create a custom resolution was impossible due to CRU preventing me from creating 390hz resolutions even when Pixel clock was noticeably lower than the 970mhz limit.

My only way to tweak VT was with the Nvidia Panel, I got a +100VT bump from 1100 to 1200, nothing drastic but it does slightly reduce crosstalk.

1203 was the real VT limit but it created a weird tear line in the top part of the screen so I settled with 1200, 1204 is out of range, also reducing HT to increase pixel clock headroom didn't bring any benefit or increase in VT from my testings.

Here's my timings:

[tlp]

text

IIRC ToastyX said that this is a glitch with the nvidia driver(not being able to see the displayport extension blocks).

What works for me is deleting all the extension blocks/resolutions and then copying the 390hz timings that the nvidia control panel displays into a DisplayID 1.3 extension block.

Example:

I can't get it do grab a signal above 400Hz Vertical, 469.xxx kHz Horizontal, 975.94 MHz Pixel Clock or 33xx Vertical Total. I'm assuming these are some arbitrary limits in the firmware, unless I'm up against the Displayport spec limits?

I'm not sure if I've been going about it the right way as I've ran into some oddities with large vertical totals. For example if I select the "Pixel Clock" radio button and increase the Vertical total to the absolute highest values that the monitor will accept, it will start taking longer for the monitor to change mode and sometimes it will display "no signal" but then work on a subsequent attempt?

Another peculiar behaviour I had was that I had significantly increased latency, way worse than V-Sync latency, after a modeswitch. But after tabbing out to 400hz desktop and back into the game at 142.xxxHz it felt normal again, which might be a quirk of the game used I suppose? Or maybe some sort of fall-back feature to avoid the "no signal" blackscreen.

I've also seen the tearing thing you mentioned but I assumed it was because I have V-Sync disabled globally in NVCP.

Hopefully this was somewhat legible.

EDIT: Make sure to disable Freesync in the monitor OSD or you'll just get "No Signal" when attempting this. Not sure if you can extend the Freesync range, didn't work for me but idk what I'm doing.

[axaro1]

IIRC ToastyX said that this is a glitch with the nvidia driver(not being able to see the displayport extension blocks).

What works for me is deleting all the extension blocks/resolutions and then copying the 390hz timings that the nvidia control panel displays into a DisplayID 1.3 extension block.

Thank you for the explanation, I'll give it a try.

I'm not sure if I've been going about it the right way as I've ran into some oddities with large vertical totals. For example if I select the "Pixel Clock" radio button and increase the Vertical total to the absolute highest values that the monitor will accept, it will start taking longer for the monitor to change mode and sometimes it will display "no signal" but then work on a subsequent attempt?

Another peculiar behaviour I had was that I had significantly increased latency, way worse than V-Sync latency, after a modeswitch. But after tabbing out to 400hz desktop and back into the game at 142.xxxHz it felt normal again, which might be a quirk of the game used I suppose? Or maybe some sort of fall-back feature to avoid the "no signal" blackscreen.

It's not the first time I hear about timing tweaks affecting latency in scenarios where it should technically reduce it, from my understanding of QFT increasing VT should always be beneficial to latency and crosstalk, maybe Chief can clarify this odd behaviour.

By "modeswitch" do you mean switching between VRB ON/OFF,VRR ON/OFF or just swapping between different refresh rates?

I wish I had an LDAT tool... I'm not noticing any issue in terms of latency with VT set to 1200, actually some minor improvement assuming that it's perceivable and not placebo (it's probably in the realm of microseconds so most likely placebo, either way no regression).

[lyrill]

i mean this in the most helping initiative: don't you guys think that maybe whatever these tweaks you do Acer and that panel brand they used also knows? so they try to limit you doing further things and thereby asserting more control on how the market progress is paced?

btw yes I agree with you, we always said it's supposed to be max whatever's intuitively supposed to be maxed. all those debates about brightness, within the context of using this monitor alone, is kinda noises tbo. just use it. it just works...(and I am the last guy in any room that want to sound reductive believe me)

[tlp]

By "modeswitch" do you mean switching between VRB ON/OFF,VRR ON/OFF or just swapping between different refresh rates?

A change in resolution/refreshrate that isn't just going between gpu-scaled resolutions is what I meant.

So desktop=400Hz, ingame=14xHz, tabbing in and out of the game will make the monitor go black and renegotiate signal is what I called "modeswitch".

What was weirding me out was that it would be completely unusably laggy, and then after an alt-tab it felt really good. It honestly made me want to not mess with my own custom resolutions for a bit. :/

from my understanding of QFT increasing VT should always be beneficial to latency and crosstalk

This was also how I understood it from reading Chief's guide, but it was not reflected in my experiences with this monitor, although I cannot say for sure since I didn't take any pictures of the crosstalk, I was just "eyeballing" it.

However, from my recollection, higher Vertical Totals seemed to hurt the crosstalk performance at 144Hz. The "sweetspot" seemed to be somewhere between 170-190Hz for minimum crosstalk.

The missing ingredient is probably the ability to tweak the strobe settings within the monitor, these settings are unfortunately not exposed within the OSD nor the Service Menu.

I'd be interested to know why the signal negotiation takes longer at the very limit of Vertical Totals that the monitor will accept. If I were use terminology that's common in other "overclocking" scenarios, is it a "stability" issue? Is this a thing for monitors?

Lastly I thought I should point out that I did this with the "Overclock" setting Disabled in the OSD. I've been pondering if this setting does anything other than supply a slightly different EDID. Sure seems like not. But with "Overclock" enabled I can't get into my motherboards BIOS nor windows Safe Mode, so enabling it just makes life difficult since you CANNOT reach the OSD without an input signal being present, which is very annoying.

[lizardpeter]

I've been sticking to OD Extreme.

Same. I have no complaints.

[Diesto]

I’m actually leaning towards the Nitro a bit more now.

I can tell you from my limited experience with it that it's really fast. On the UFO test at 1920 pixels per second, there's almost no visible ghosting at all. However, this is with my own settings and the known contrast reduction trick. I have the overdrive on extreme, the brightness at 100, max brightness on, black boost at 10, and contrast at 0 (increase this if you need it to be brighter).

I am alternatively trying overdrive on extreme, the brightness at 100, max brightness on, black boost at 10, contrast at 10, and BFI on extreme.

They are both very solid options. I am not sure which I like more. I will have to do some testing.

what is "the known contrast reduction trick" ?

[lyrill]

I’m actually leaning towards the Nitro a bit more now.

I can tell you from my limited experience with it that it's really fast. On the UFO test at 1920 pixels per second, there's almost no visible ghosting at all. However, this is with my own settings and the known contrast reduction trick. I have the overdrive on extreme, the brightness at 100, max brightness on, black boost at 10, and contrast at 0 (increase this if you need it to be brighter).

I am alternatively trying overdrive on extreme, the brightness at 100, max brightness on, black boost at 10, contrast at 10, and BFI on extreme.

They are both very solid options. I am not sure which I like more. I will have to do some testing.

what is "the known contrast reduction trick" ?

He mentioned that previously. I felt it's a bit extreme, haven't tried it myself until. lowering both is a good balance point to start. I'm trying it now in browser and it looks as if it's a bit better clarity on the white parts, because obviously maxing brightness doesn't alter the tone of the color as much as changing contrast, which would be bleach white and unusable if maxed.