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vertical total of 2625?

Posted: 17 Aug 2014, 06:19
by newuser379t
Hello, i've been experimenting with the vertical total using toastyx CRU and toastyx pixel patcher and have managed to get a vertical total of 2625 at 120hz. I find this weird because when i was experimenting with it a month ago i couldn't even achieve a vertical total of 1502 with a horizontal total of 2200 at 120hz. The CRU program itself even says the configuration is active and i only have 1 detailed resolution set. Am i doing something wrong or am i actually achieving these results?

Monitor - Benq XLT2411T
AMD graphics card
Graphics card driver set at 120hz
Some more proof - http://i.imgur.com/v2NvQ2H.jpg

monitor is crisp and clear whereas before there were many artifacts at VT1500 and a black screen at VT1502. VT2625 is the highest i can go until the CRU program stops me.

My wild theory on how i am achieving these results is the hdmi to dvi cable i bought a while back - .http://www.ebay.com.au/itm/261505830537 ... 1439.l2649

Re: vertical total of 2625?

Posted: 17 Aug 2014, 10:17
by trey31
A 655.20MHz pixel clock on a DVI to HDMI ebay cable?? ;)

Re: vertical total of 2625?

Posted: 17 Aug 2014, 10:59
by newuser379t
my monitor is connected using a standard dvi cable. The dvi to hdmi is connected on my monitor but not the tv. I'll test this more tommorow but i can't think of any other possibility.

Re: vertical total of 2625?

Posted: 17 Aug 2014, 20:49
by newuser379t
Sorry i meant standard dvi is connected from pc to monitor and dvi to hdmi cable is only connected to pc (not monitor or tv). I tried unplugging the dvi to hdmi cable to see if it has any effect but nope, everything is the same so i don't know how i am achieving these results. Maybe it's the device driver?

Re: vertical total of 2625?

Posted: 17 Aug 2014, 21:00
by Chief Blur Buster
According to my math calculations, if you are achieving VT2625 (which I think is unlikely), you are far overclocking DVI far beyond its specifications. Dotclock, as in number of pixels output per second, is insanely high at 655Mhz according to my math.

Your dotclock would be (horizontal total X vertical total X refresh rate). Since common horizontal total for 1920x1080 is about 2080, that means you would be doing 2080x2625x120 = 655 megahertz dotclock

Dotclock for 1920x1080 is typically (2080x1149x120) = 286 megahertz dotclock

QNIX overclocked to 120Hz at 2560x1440 is roughly (2600x1450x120) = 452 megahertz dotclock

I'm not certain that your video card is actually outputting a true 655 megahertz dotclock over the video cable to the monitor, so some decimation may be occuring, e.g. within the graphics card, or some other chain. The highest genuine VT that worked on the BENQ is 1502 at 120Hz, and it reportedly can reach VT1600 or VT1800 at some lower refresh rates, according to some tests done (forgot which specific refresh rate).

Done properly (visible frame first followed by blanking interval) large vertical totals will primarly help input lag of VSYNC ON situations, by accelerating the scanout of the visible frame (only on displays with real-time scanout, such as CRTs and certain LCDs such as the BENQ Z series), as the VSYNC OFF situation will not benefit noticeably from this since VSYNC OFF means immediate splicing of the refresh (where the tearlines occurs).

Re: vertical total of 2625?

Posted: 18 Aug 2014, 03:28
by masterotaku
I was going to post yesterday, but somehow I forgot. I tried creating a custom resolution with VT2625. I think the monitor is ignoring that huge vertical total, as the maximum strobe phase doesn't change compared to VT1502 and crosstalk isn't better. The image displays correctly, but the Nvidia Control Panel doesn't want to remember that resolution when I tell it to save it.

Re: vertical total of 2625?

Posted: 18 Aug 2014, 07:14
by Falkentyne
It's using the default vertical total and ignoring that resolution you made.

I just tried making a 120hz resolution with the exact same VT settings and timings you did, on my 290X, in CRU, but my default refresh rate was 100. When I rebooted, even though the 120hz showed in CRU, there was was no 120hz pulldown in the catalyst CC. It was completely missing.

that would explain why Masterotaku's Nvidia CP refused to even save the resolution...it was invalid.

Most likely, since that was the only resolution you had, it used 120hz but defaulted to standard stock timings.
The same thing happens if you use a >329 MHz dot clock without using the patcher when increasing the vertical total...it defaults to the 1125 VT instead of using your custom one.