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:lol37 wrote:i would still consider modding a XL2411/XL2420Z and then strobe it to 200+hz
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.