Successful Overclock 60Hz -> 180Hz of Laptop LCD!

Talk about overclocking displays at a higher refresh rate. This includes homebrew, 165Hz, QNIX, Catleap, Overlord Tempest, SEIKI displays, certain HDTVs, and other overclockable displays.
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Chief Blur Buster
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Re: Successful Overclock 60Hz -> 180Hz of Laptop LCD!

Post by Chief Blur Buster » 17 Jan 2014, 14:24

lol37 wrote:i would still consider modding a XL2411/XL2420Z and then strobe it to 200+hz
Strobing doesn't work well when the pause between refreshes isn't big enough to let LCD pixel transitions finish before the next refresh. The LCD becomes in a perpetual state of ghosting, much like three refreshes overlapped:

Image

If you have plenty of time between refreshes, your LCD scanning looks like this high speed video of a strobeable LCD. But if you don't have enough time between refreshes to let GtG pixel transitions finish, your LCD scanning looks like this high speed video of an UN-strobeable LCD. Currently, most overclocked LCDs will resemble the UN-strobeable LCD during high speed video, and thus would not be suitable for strobing.

Strobing becomes progressively worse at higher refresh rates on my BENQ XL2720Z. Strobing is cleanest at 75Hz, more ghosting at 100Hz, lots of ghosting at 144Hz. (ghosting = strobe crosstalk = leakage of unfinished LCD pixel transitions to next refresh).

You've got a strobe-quality tradeoff. Eventually, strobing becomes so poor quality, that you prefer to turn off strobing. Currently, 180Hz and 240Hz LCDs likely looks better non-strobed, while fast-enough specially designed 120Hz gaming LCDs are finally fast enough for high-quality CRT-quality nearly-perfectly-ghostfree strobing.

That said, if an LCD overclocks to 180Hz without too much streaking, then it's likely strobeable at, maybe 120Hz or maybe even 150Hz. You will want to use ToastyX or nVidia Custom Resolution to make your Vertical Total much bigger, so you have a long, 2 millisecond blanking interval pause between refreshes. This lets your LCD pixels finish settling, before you flash the strobe backlight. Strobing may actually work well at ~120-150Hz on your LCD, since you have enough bandwidth headroom to add a fat blanking interval at those lower refresh rates, to let pixel transitions finish BEFORE the next refresh begins. For TN LCDs, you want a blanking interval lasting about 2 milliseconds between refreshes, and this can be accomplished on some LCDs via a large "Vertical Total" in nVidia Custom Resolution Utility, and then calibrating the strobe timing via test patterns (e.g. http://www.testufo.com/blurtrail in Height->Full Screen) to avoid the strobe-phase bug similiar to the one found in the early beta XL2720Z firmware. Often, due to pixel lag, you want to strobe slightly late relative to blanking interval (which means keeping the backlight early into the next refresh cycle) because the human visible pixel transitions are delayed relative to the timing of the LCD electronic refresh. All of this, of course, is knowledge ensconed in Electronics Hacking: Creating a Strobe Backlight.
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lol37
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Re: Successful Overclock 60Hz -> 180Hz of Laptop LCD!

Post by lol37 » 17 Jan 2014, 14:31

Too bad...
i saw 8/9 light power from backlight are blocked from liquid crystal combined with color filters, it would mean with a 100% emissive display ( like OLED ), strobing won't be a problem for highers refresh rate
there's also PHOLED whom could reach 100% efficiency, beating easily CRT display
Last edited by lol37 on 17 Jan 2014, 14:37, edited 1 time in total.

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Re: Successful Overclock 60Hz -> 180Hz of Laptop LCD!

Post by Chief Blur Buster » 17 Jan 2014, 14:35

lol37 wrote:Too bad...
Not necessarily; it just lowers your max strobeable refresh rate, and that number may still be much higher than 60Hz!

Strobing may actually work well on your laptop LCD at ~120-150Hz on your LCD, if you do these tricks:
(1) Enlarge your Vertical Total to give you a longer 2 millisecond "blanking interval" pause between LCD refreshes (LCD GtG pixel settling time before strobe edgelight flash). This will make it impossible to do it at 200Hz, but you have headroom to easily be able to do at somewhere ~120-150Hz
(2) Simple microcontroller/electronics modification to flash the laptop LCDs edgelight for about 1ms-2ms, timed relative to the blanking interval. (with a strobe phase adjustment, to delay the strobe an exact amount of time beyond exact beginning of exact VSYNC timing, to compensate for lag in visibility of pixel transitions).

You are super lucky to get flawless 200Hz on an unmodified laptop LCD.
Modifications, alas, will be needed, for proper strobing, but 200Hz+TN automatically means a perfect candidate for homebrew strobing at a somewhat lower stroberate (but still higher than 60Hz).
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Re: Successful Overclock 60Hz -> 180Hz of Laptop LCD!

Post by lol37 » 17 Jan 2014, 14:39

Chief Blur Buster wrote:
lol37 wrote:Too bad...
Not necessarily; it just lowers your max strobeable refresh rate, and that number may still be much higher than 60Hz!

Strobing may actually work well on your laptop LCD at ~120-150Hz on your LCD, if you do these tricks:
(1) Enlarge your Vertical Total to give you a longer 2 millisecond "blanking interval" pause between LCD refreshes (LCD GtG pixel settling time before strobe edgelight flash). This will make it impossible to do it at 200Hz, but you have headroom to easily be able to do at somewhere ~120-150Hz
(2) Simple microcontroller/electronics modification to flash the laptop LCDs edgelight for about 1ms-2ms, timed relative to the blanking interval. (with a strobe phase adjustment, to delay the strobe an exact amount of time beyond exact beginning of exact VSYNC timing, to compensate for lag in visibility of pixel transitions).

You are super lucky to get flawless 200Hz on an unmodified laptop LCD.
Modifications, alas, will be needed, for proper strobing, but 200Hz+TN automatically means a perfect candidate for homebrew strobing at a somewhat lower stroberate (but still higher than 60Hz).
by this way it unavoidably adds input lag, but i guess we have no choice here !

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Re: Successful Overclock 60Hz -> 180Hz of Laptop LCD!

Post by Chief Blur Buster » 17 Jan 2014, 14:56

lol37 wrote:by this way it unavoidably adds input lag, but i guess we have no choice here !
The most efficient possible strobe backlights (including LightBoost/ULMB) adds about an average of ((1/Hz)*0.5)ms input lag. So if you strobe at 150Hz, you're adding an average of 3.3ms of input lag. At around 150Hz, strobing is well worth it, as the motion clarity allow you to react faster to enemies during gaming, outweighing the strobe lag.

BTW, for creating custom resolutions with long blanking intervals (for homebrew strobe modifications), the formula for NVIDIA Custom Resolution Utility or ToastyX CRU is as follows:

Idle time between refreshes = (1/monitor Hz) * ((Vertical Total – Vertical Resolution) / Vertical Total)

The bigger the better. It depends on your LCDs' resolution and target Hz. For 1080p at 100Hz, to create a 2 millisecond pause between refreshes, you want a Vertical Total of about 1350. I actually now use this on my BENQ XL2720Z to reduce strobe ghosting -- it works on my BENQ XL2720Z Blur Reduction (BENQ's clone of LightBoost)! LightBoost uses a different technique (internally accelerated scanouts) of inserting pauses between refreshes. But homebrew strobe LCD hacks / modders can use larger Vertical Totals to externally accelerate the LCD scanout and insert longer pause between refresh cycles. This lets LCD GtG transition settle down before strobe flash before the next refresh cycle.
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Re: Successful Overclock 60Hz -> 180Hz of Laptop LCD!

Post by Chief Blur Buster » 17 Jan 2014, 15:36

I was thinking that this overclockability would be very good for AMD FreeSync, where you run the LCD at a variable refresh rate all the way between 30Hz through 200Hz, in a huge variable-refresh-rate range.
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Re: Successful Overclock 60Hz -> 180Hz of Laptop LCD!

Post by Chief Blur Buster » 17 Jan 2014, 16:49

exa wrote:
Chief Blur Buster wrote:
slick8 wrote:How is this done?, is there a tut?
Blur Busters, being "everything better than 60Hz" (overclocking, gsync, lightboost, etc) is currently developing new overclocking tutorials that will be published in the near future.

1. Pick a favourite custom resolution utility:
NVIDIA Custom Resolution Utility (easiest, no reboot needed)
ToastyX Custom Resolution Utility (universal, need reboot)
PowerStrip Utility (for legacy systems)
2. Open the utility, set refresh rate to a higher refresh rate. Test the refresh rate.
3. Keep raising the refresh rate until it starts glitching or blacks out. Then back off.
4. Verify it works without frame skipping at http://www.testufo.com/frameskipping
5. If it isn't frame skipping, your refresh rate overclock is successful!

If you plan to overclock 1440p, you may need to unlock your drivers using http://www.monitortests.com so you're not hitting against your drivers dot clock limit. This allows you to overclock 1440p and 4K more significantly than you would otherwise, by pushing DVI cables beyond their limits. The use of Monoprice DVI cables, or other thick premium DVI cables, will help you overclock more, provided your monitor does not have a safety lock on refresh rate preventing you from overclocking.

Most displays with safety locks, won't let you overclock. But a few displays do let you easily overclock a lot (e.g. QNIX QX2710 Evolution 2, X-Star DP2710, Catleap 2B, Overlord Tempest X270OC). That said, if far less motion blur is very important, strobe backlights are superior to overclocking (LightBoost has far less motion blur than a 180Hz overclock). However, you can get improvement in motion fluidity, and far less input lag with overclocking!
When I try overclocking my monitors it does work but the resolution gets smaller or it takes the whole screen but it gets blurry, does this means that it won't work ? Or I can play with manual settings ?
Hello exa,
Welcome to the forums!
I've replied here: What are the Side Effects of Overclocking your Display?
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Re: Successful Overclock 60Hz -> 180Hz of Laptop LCD!

Post by trey31 » 17 Jan 2014, 17:50

forums.blurbusters.com

Seriously, one of my new favorite sites!


Also, for your tutorial about overclocking TVs using NVIDIA CP, I've got a ton of random notes I made while testing custom EDIDs. I'll compile it all hopefully pretty soon in an easy to read, short bullet list. But basically, NVIDIA CP resolutions aren't always what they appear to be when using "Auto" as the timing for custom resolutions/refresh rates. In fact, they can do some super weird stuff. As far as I can tell, none of which is beneficial. Unless a game or program is ran in a window rather than fullscreen. Either way there are some do's and don'ts that should probably be followed. Until I compile the notes, best advice is to always take the time to use a manual timing when "testing" and saving custom resolutions/refresh rates if the resolution is anything other than the display's native res.

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Re: Successful Overclock 60Hz -> 180Hz of Laptop LCD!

Post by lol37 » 18 Jan 2014, 15:06

just one question, is there any TN panel upcoming featuring sub 1ms range GTG ? (will it be a great change ?)
i think it would be better to work their worst-case pixel transition !
also are the XL2420Z and the XL2411Z coming with the new firmware ?

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Re: Successful Overclock 60Hz -> 180Hz of Laptop LCD!

Post by Chief Blur Buster » 18 Jan 2014, 16:10

lol37 wrote:just one question, is there any TN panel upcoming featuring sub 1ms range GTG ? (will it be a great change ?)
Blue-phase LCDs. But they are still experimental. OLED is currently farther ahead than those, so OLED will probably beat those.
lol37 wrote:i think it would be better to work their worst-case pixel transition !
That's correct. The new 1ms LCDs by ASUS/BENQ actually do it far better than yesterday's 2ms LCDs (like my Samsung 245BW from Year 2006); although the best case is almost unchanged, the worst case GtG curve is far better looking than the worst case GtG from more than five years ago. You still have pixel ripple for several milliseconds, which is extremely hard to clean up, but you're already more than 90% finished transitioning most colors by 1ms. The problem is that 90% completeness = 10% ghosting (strobe crosstalk)
If you're finished by 98%, you got 2% ghosting (strobe crosstalk), and so on.

They had to fix as many worst-case GtG as possible, to make LCDs compatible with 3D shutter glasses, and compatible with strobe backlights, by finishing as much pixel transitions as much as possible, before the next refresh cycle. It's been a major engineering challenge for LCD and it was only recently (2012) that LCD now existed that has CRT motion clarity.
lol37 wrote:also are the XL2420Z and the XL2411Z coming with the new firmware ?
I've been telling BENQ to expedite.
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