Display Port v1.2 (Maximum Pixel Clock Rate)?

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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PanzerIV
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Display Port v1.2 (Maximum Pixel Clock Rate)?

Post by PanzerIV » 05 Jun 2015, 23:45

Hi! To make it short, I had a DVI-D cable and was able on my (BenQ XL2420Z) to go up to 374Mhz without problem once I'd use the (AMD Pixel Clock Patch v1.3.3) but then my cable just died from unplugging it somehow and I went to the dollarstore and bought a cheap 3$ (3D HDMI Cable) so I'd guess it is at least v1.3 which is still suppose to go up to 340Mhz but I keep getting "Out of range" message when I go above 85Hz so WTF!? That is my first issue.

The second one is mostly a question. I've noticed my monitor and R9 280X are both DP v1.2, but I have no idea what is the highest pixel clock rate possible to use for those cables if I want to OC my monitor. It is fantastic if it is 540Mhz but if it is 162 or 270 then it's really bad and I want to know before buying such cable as they tend to be very rare and overpriced! "DP uses one, two, or four differential serial data paths to carry the video and audio. The data is self-clocking at a bit rate of 1.62, 2.7, or 5.4 Gbits/s per path using clock rates or 162, 270, or 540 MHz."

Thanks a lot in advance for the info.
Alex
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kodachrome
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Re: Display Port v1.2 (Maximum Pixel Clock Rate)?

Post by kodachrome » 19 Jul 2015, 19:42

Generally due to the scaler you cannot overclock DP inputs on the monitor side, only via adapters from DP on your PC to DVI on the monitor side. So there is no point in pursuing that avenue. On your first issue.. prolly easiest to just get a proper DVI cable again?

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PanzerIV
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Re: Display Port v1.2 (Maximum Pixel Clock Rate)?

Post by PanzerIV » 19 Jul 2015, 20:40

kodachrome wrote:Generally due to the scaler you cannot overclock DP inputs on the monitor side, only via adapters from DP on your PC to DVI on the monitor side. So there is no point in pursuing that avenue. On your first issue.. prolly easiest to just get a proper DVI cable again?
So pretty much it doesn't matter if I use DP or DVI behind my video card, as long as I am connected through DVI behind the monitor???

I never heard before that it wasn't even possible to overclock the DP input, but only the DVI. Since when is it like this and is it on any monitor?! Somehow it seems to be working as I can be at 312Mhz "100Hz" without problem now and I confirm that it works on TestUfo.

I had a problem since I use a DP cable, that when I was waking up from sleep, the resolution would go from 1920x1080 to something extremly tiny and mess all my icons on the desktop until I'd reboot, but it never did that if I'd shutdown and start again the computer. Now however, I think it has been fixed when I wake up from sleep since I've updated the driver to the latest one.
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Falkentyne
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Re: Display Port v1.2 (Maximum Pixel Clock Rate)?

Post by Falkentyne » 19 Jul 2015, 21:21

HDMI can not do more than 60hz at higher than 720p. You may be able to get 120hz at 480p or 720p or 1024x768 but absolutely no higher.

The pixel clock is not what determines the maximum refresh rate. it's far more complicated than that.
https://en.wikipedia.org/wiki/HDMI#Version_1.4

Also you CAN overclock the DP inputs just like DVI.
DP 1.2 has a theoretical pixel clock limit of 480 MHz at 6 bit color and 360 MHz at 8 bit color, yet you can exceed this at your own risk.
Dual link DVI has a pixel clock limit of 330 MHz, unless you patch the driver. In the real world, both DP and DVI have the same absolute limits.

I have a 389 MHz 125hz (Vertical total 1498) resolution for 1920x1080.
This works both on DVI (patched) and DP.

DP does not require a pixel clock patcher like DVI.

Your problem with DP and sleep mode is the firmware. You are using V2 or V3, right?
The sleep bug with DP was fixed in version 4 firmware, and an extra AMA high mode (lightboost like AMA) was added only for blur reduction (would have been nice if it worked without blur reduction, but whatever).

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PanzerIV
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Re: Display Port v1.2 (Maximum Pixel Clock Rate)?

Post by PanzerIV » 19 Jul 2015, 21:46

I am using the V2 as I've been shipped a wrong V1 when I first bought the monitor, then BenQ sent me a new unit with V2 as it appears it was too complicated for them to just let me drive 30 minutes to their office in Montreal to have it updated. I did not know there was a V3 and even a V4 available but is it still the same impossible "ultra complicated" method to update the firmware? It's dumb as they got USB ports on the side but they appear to be totaly useless. I never had any trouble updating the bios of my motherboards or the firmware of everything I have but then when it come to this stupid monitor, there's like nothing you can do without special and expensive tools (-_-)

What you mean about the new (AMA High Mode). I have (Off, High, Premium) but there's a new one above Premium or they just improved uppon the High mode? The reviews said to stay at High because there was overshoot at Premium and no extra gain that was worth the glitches.

At least I guess it is good to know that the issue isn't software-side or isn't my computer as I really tryed everything that was possible and was starting to turn crazy about it!
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Falkentyne
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Re: Display Port v1.2 (Maximum Pixel Clock Rate)?

Post by Falkentyne » 19 Jul 2015, 22:21

No the V4 "lightboost quality" AMA high mode is hidden. It's a new toggle for V4.
You enable blur reduction, set AMA to "high" after MBR is enabled, then lower the contrast to lower than 20 (otherwise the normal ghosting will be too high)

*EDIT*
THIS ONLY APPLIES TO THE XL2720Z!
The 2420Z and 2411Z just have a 'barely' toned down AMA if you do this, slight improvement and more improvement at 60hz refresh rate, while 2720Z uses a lightboost type calibration for this.

The DP bug affects all the monitors. The loss of signal fix was mentioned by Benq (by someone who sent their V3 back for this bug) as a fix for V4. The AMA toggle are undocumented. XL2420Z and XL2411Z were giving a "slightly" reduced AMA high after this toggle. XL2720Z was given lightboost quality AMA after this toggle. Someone said that on the 24" screens. non blur reduction default AMA was massively improved (not so for 27" though).

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PanzerIV
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Re: Display Port v1.2 (Maximum Pixel Clock Rate)?

Post by PanzerIV » 19 Jul 2015, 23:11

It's weird as I only see V2 from 2013 being available at Benq's website, unless the V3 and V4 are hidden betas (-_-)
http://gaming.benq.com/downloads

Anyway, even if I get to find it, is there a way that a "normal user" can update the firmware without sending it to BenQ or buying 100$ hardware to use it only 1 time? :?
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Falkentyne
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Re: Display Port v1.2 (Maximum Pixel Clock Rate)?

Post by Falkentyne » 20 Jul 2015, 00:07

XL2411Z v4 was dumped by whitestar (directly from his unit shipped from Benq)
http://forums.blurbusters.com/viewtopic.php?f=13&t=2190

Others are here
http://forums.blurbusters.com/viewtopic.php?f=13&t=1969

RLBURNSIDE
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Re: Display Port v1.2 (Maximum Pixel Clock Rate)?

Post by RLBURNSIDE » 20 Nov 2015, 10:33

Falkentyne wrote:HDMI can not do more than 60hz at higher than 720p. You may be able to get 120hz at 480p or 720p or 1024x768 but absolutely no higher.
False. I can send 100hz or so at 1280x1024 to my projector, which looks bad but I know for a fact that HDMI 1.4 chips can send 120hz at 1080p / 444 / 8-bit. That's how the PS4 is driving the Morpheus, after all. And many people drive 120hz at 1080p with older video cards through HDMI to their LCD monitors, for about 5 years now.

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