Persistence and input lag and a bit more...

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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BullDoser
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Joined: 09 May 2014, 08:12

Persistence and input lag and a bit more...

Post by BullDoser » 12 May 2014, 17:19

Hello,

Would be nice if someone could give me answers to these questions:

1. Would having 0.5ms Persistence in "blur busters strobe utility" instead of 5ms give me 4.5ms less input lag? Or is it all about Brightness/Motion blur?
2. Are there any tweaks I should do to reduce motion blur/input lag or just anything at 144hz? (Benq XL2720z, already calibrated my monitor and reduced crosstalk with BBSU). Not really looking to go to 120hz, though.
3. I have seen that if you set Herz to 120 instead of 144, you can use VT1350 trick, can anything be done when using 144hz? Also, why is it 1350 and not like 1360? What is a limiting factor here? Can't I increase these numbers on 144hz? Seems it won't allow me to reach 1350, but why not just increase it by like 20 or so? (Default is 1125, I believe) Would using a displayport instead of DVI change anything?
4. I understand that earlier strobe phase gives less input lag than later strobe phase. But are we talking about 1-2ms, or is it something bigger like 5ms or so?
5. I tried overclocking monitor to 160hz without a luck. It said "out of range". What is the maximum pixel clock that this monitor can handle?

Thanks!

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Chief Blur Buster
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Re: Persistence and input lag and a bit more...

Post by Chief Blur Buster » 13 May 2014, 01:56

1. Persistence has nothing to do with input lag. It is all about motion blur. See PHOTOS: 60Hz vs 120Hz vs LightBoost for the relationship between persistence and motion blur.

2. The difference between 120Hz and 144Hz is only 1-2ms. Hz does not always determine motion blur. There is far less motion blur at 100Hz 1ms persistence than 144Hz 5ms persistence. Enabling strobing at all modes adds about half a refresh cycle average lag, much bigger than the difference between 144Hz and 120Hz.

3. No, and no. The limiting factor is dotclock (number of pixels refreshed per second, including the offscreen blanking interval). It is impossible to go beyond. 120Hz+VT1350 actually roughly equals the dotclock of 144Hz alone. The larger vertical total forces a faster top-to-bottom scan out of LCD plus a longer pause between refreshes. This allows pixel transitions to be more fully complete between refresh cycles. The strobe crosstalk (razor sharp ghost effects) in blur reduction diminishes/disappears at lower refresh rates, so that's why when the motion quality is priority then we use lower refresh rates. However, you have to sacrifice motion quality if you want minimum possible lag, e.g. 144Hz and earliest strobe phase (but worse double image effect that may slow down reaction times, depending on your gameplay types/tactics). Adding only a few lines to the VT is worthless as adding only 40 would shift the crosstalk downwards only 40 pixels. The ghosting zone is much bigger than that.

4. About 1-2ms. Merely enabling blur reduction gives you the bigger average increase in lag. At 144Hz, the increase between blur reduction off/on is approximately 3ms average.
- If motion blur is not important, minimum lag occurs at 144Hz with blur reduction turned off. It is about 3ms less lag.
- If fixing motion blur is important, I strongly recommend 120Hz+VT1350 or even VT1500 which actually is only a millisecond extra lag over 144Hz but may permit faster reaction times in motion-critical situations (e.g. Scout character in team fortress 2) out-compensating the lag.
However, it is a matter of personal preference.

5. 144Hz is the highest I was able to achieve.
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