DisplayPort vs HDMI vs DVI-Dual Link

[MonarchX]

I've seen some info that DisplayPort may reduce the amount of input lag in comparison to HDMI and DVI-Dual Link. I didn't believe it, but maybe I was wrong. DisplayPort can also support more colors or so say the system specs, but AFAIK, that doesn't mean that the monitor itself supports that many. For 120Hz displays such as Eizo FG2421, would there be an advantage to use one port over another?

[Chief Blur Buster]

I've seen some info that DisplayPort may reduce the amount of input lag in comparison to HDMI and DVI-Dual Link. I didn't believe it, but maybe I was wrong. DisplayPort can also support more colors or so say the system specs, but AFAIK, that doesn't mean that the monitor itself supports that many. For 120Hz displays such as Eizo FG2421, would there be an advantage to use one port over another?

The difference of input lag between DisplayPort vs HDMI vs DVI is less than 1 millisecond. So it's not a significant deal.

However, DisplayPort has the convenient ability to pre-transmit frames faster than a refresh cycle. Not all monitors take advantage of this, but some monitors (e.g. GSYNC) takes advantage of a faster transmission by pushing the frame from the computer to the monitor as fast as possible, independently of the current refresh rate. In the real world, the latency differences of different cable technologies usually won't be measurable in the fluctuations of other parts of the input lag chain.

<advanced-display-geek-tip>There is a way to reduce input lag further even on DVI via large vertical total tweaks (ToastyX Pixel Patcher + ToastyX CRU or NVIDIA Custom Resolution), such as using a 1502-scanline vertical total for a 1920x1080 signal, to force a higher dotclock at the same refreshrate/same framerate. This creates a higher dotclock (by padding the end of a refresh cycle with a large synchronization interval) that transmits the frame faster from the GPU to the monitor, reducing average input lag -- but only by one millisecond -- and impacts VSYNC ON more than VSYNC OFF -- and only on certain models of monitors capable of syncing to these unusually large blanking intervals -- and of those that do, properly scans out the refreshes out faster without a higher refresh rate. One example is the BENQ Z-Series monitor in Instant Mode</advanced-display-geek-tip>

TL;DR: The differences in input lag for DVI vs HDMI vs DisplayPort is less than a millisecond difference, for a given resolution & refresh.

[MonarchX]

Gotcha. Is there any other reason to use one or another? I recall you advising to use DVI Dual-Link in some thread, but maybe I was wrong...

[Kirayamato]

I've seen some info that DisplayPort may reduce the amount of input lag in comparison to HDMI and DVI-Dual Link. I didn't believe it, but maybe I was wrong. DisplayPort can also support more colors or so say the system specs, but AFAIK, that doesn't mean that the monitor itself supports that many. For 120Hz displays such as Eizo FG2421, would there be an advantage to use one port over another?

The difference of input lag between DisplayPort vs HDMI vs DVI is less than 1 millisecond. So it's not a significant deal.

However, DisplayPort has the convenient ability to pre-transmit frames faster than a refresh cycle. Not all monitors take advantage of this, but some monitors (e.g. GSYNC) takes advantage of a faster transmission by pushing the frame from the computer to the monitor as fast as possible, independently of the current refresh rate. In the real world, the latency differences of different cable technologies usually won't be measurable in the fluctuations of other parts of the input lag chain.

<advanced-display-geek-tip>There is a way to reduce input lag further even on DVI via large vertical total tweaks (ToastyX Pixel Patcher + ToastyX CRU or NVIDIA Custom Resolution), such as using a 1502-scanline vertical total for a 1920x1080 signal, to force a higher dotclock at the same refreshrate/same framerate. This creates a higher dotclock (by padding the end of a refresh cycle with a large synchronization interval) that transmits the frame faster from the GPU to the monitor, reducing average input lag -- but only by one millisecond -- and impacts VSYNC ON more than VSYNC OFF -- and only on certain models of monitors capable of syncing to these unusually large blanking intervals -- and of those that do, properly scans out the refreshes out faster without a higher refresh rate. One example is the BENQ Z-Series monitor in Instant Mode</advanced-display-geek-tip>

TL;DR: The differences in input lag for DVI vs HDMI vs DisplayPort is less than a millisecond difference, for a given resolution & refresh.

can you explain how to do this for my benq xl2420te you said benq z series in isntant mode is an example for this procedure so mine is doing this automatically or what?

[orik]

<advanced-display-geek-tip>There is a way to reduce input lag further even on DVI via large vertical total tweaks (ToastyX Pixel Patcher + ToastyX CRU or NVIDIA Custom Resolution), such as using a 1502-scanline vertical total for a 1920x1080 signal, to force a higher dotclock at the same refreshrate/same framerate. This creates a higher dotclock (by padding the end of a refresh cycle with a large synchronization interval) that transmits the frame faster from the GPU to the monitor, reducing average input lag -- but only by one millisecond -- and impacts VSYNC ON more than VSYNC OFF -- and only on certain models of monitors capable of syncing to these unusually large blanking intervals -- and of those that do, properly scans out the refreshes out faster without a higher refresh rate. One example is the BENQ Z-Series monitor in Instant Mode</advanced-display-geek-tip>

Is this compatible with ToastyX's Strobelight Utility you think?

I just got a BENQ XL2420T and am on my way home with it. Is the Strobelight Utility the best way to enable 24/7 backlight strobing.

[Falkentyne]

Strobelight works well on the 2420T, but does NOT work on the Z monitors (you can get lightboost mode (for less crosstalk than benq blur reduction, but worse colors/contrast unless you're using the 2720T/2720Z 27"'s) but you need the inf override and 3d vision emulator.zip file and an Nvidia card to get LB working.

Anyway, the Vertical total tweaks are NOT compatible with lightboot. LB is unlocked by a vendor specific ddc handshake and activated by certain vertical totals: 1138 for 100 hz, 1143 for 110hz, 1149 for 120hz. 1155 'works' for 121hz on the 24" VG248QE but not for the benq (backlight pulses rapidly and cursor stutters...might possibly cause damage to the backlight), although I used a 2080 horizontal total; since the 27" 2720T uses a 2200 horizontal, I wonder if 121hz would work there. 125 hz lightboost does NOT work properly on the VG248QE. The backlight remains steady (not pulsing) but there's massive frame lag every spilt second.

I wonder why a 1155 VT is available even though lightboost is bugged here?

[flood]

<advanced-display-geek-tip>[/color][/b]

define input lag as the time between when a frame finishes rendering and when it begins to appear on the screen.

if you play with vsync off... the frames rendered during the sync interval don't get displayed. this actually makes input lag, on average, worse.

in practice this of course doesn't matter

[Chief Blur Buster]

Vertical total tweaks works on BENQ Z-Series but not LightBoost ... LightBoost already buffers the input partially and outputs a accelerated scan rate, so it's immune to vertical total tweaks (it only keys on the VT1147 and above, only as a signal to turn on LightBoost, but doesn't affect the rate of actual panel scan-out)

Input lag (mainly during VSYNC ON, not VSYNC OFF) is reduced when scan rate (also may be called 'scan velocity') is increased from a larger vertical total -- this causes a faster horizontal scanrate in KHz, in number of scanlines output per second. The ratio of time spent scanning a visible screen versus the blanking interval is pushed towards spending less time scanning-out the visible screen, if more scanlines are added to the blanking interval (porches/sync) while maintaining a vertical refresh rate. A Vertical Total of 1502 for a 1920x1080 screen, means 1080/1502ths of a refresh cycle is spent scanning out the screen, which is less time spent refreshing the screen than the usual 1080/1125ths during a default Vertical Total of 1125. This assumes the display is capable of real-time scanout from input to the LCD, like the BENQ Z-Series is.