Originally Posted by Smykster
Okay, as per Ken's request once again, I'll clear up some misinformation regarding cable bandwidth and monitor refresh rates:
My message to Ken:
KK, did some number crunching for you. The effective data rate of a dual link DVI cable is 7.92 Gbits/second. With this in mind, the highest resolution dual link DVI supports at 120hz is 1920*1200. How do we know this? 1920*1200 = 2,304,000 pixels, 2304000 x 120(hz) = 276,480,000 x 24(bit color) = 6,635,520,000 or 6.63 Gbits/sec.
For a resolution of 2560*1440, lets do the math:
2560*1440 = 3,686,400 x 120(hz) = 442,368,000 pixels per second x 24(bit color) = 10,616,832,000 bits per second or 10.6 Gbits/second.
Dual-link DVI effective data rate = 7.92 Gbits/sec
HDMI 1.3/1.4 effective data rate = 8.16 Gbits/sec
DisplayPort 1.0/1.1 effective data rate = 8.64 Gbits/sec
2560*1440 @ 120hz = 10.61=Gbits/sec which is well over all of these.
Displayport 1.2 effective data rate = 17.28 Gbits/sec
HDMI Type B effective data rate = 20.40 Gbits/sec
Those would work with 2560*1440 @ 120hz
From the write up I did, I would hypothesize that the hardware is indeed pumping out 2560*1440 @ 120hz or greater, but the bandwidth is being exceeded and the monitor is is not showing many of the frames. Just like when you're gaming at 120hz yet you have a 60hz monitor, you're missing half the frames the hardware is pumping out.
Again Smykster, it would behoove you to do some additional reading in the Catleap threads (particularly people replying to and refuting your claims) as well as some additional research overall. More than a couple times now people have pointed you to specifications that clearly indicate that Dual-link DVI is *not* limited to simply 2x the bandwidth of single-link. The same way an HDMI 1.3/1.4 (which is electrically single-link DVI) can reach effective data rates around twice that of single-link DVI (since it also does not have a hard 165MHz clock limit) dual-link DVI can also be run at any clock rate that the associated hardware and cables can handle. I get the feeling people are getting a little tired of pointing this out over and over again, so please do some thorough research to convince yourself of this fact.
If you're presuming that the monitor or card is simply frame-dropping at high refresh rates, the logic for that doesn't really pan out. Consider firstly that we have confirmation for sure that the monitors will actually accept and display refresh rates above 60. I have personally tested as high as 90Hz, and confirmed that no frame-dropping occurs; I can also visually perceive a difference between this and 81Hz (the next-lowest setting I tested). We *also* know that HyperMatrix has tested the monitors up to roughly 130Hz; his behaviour at these high refresh rates is consistent with running into sync or bandwidth limitations (glitching, artifacting, etc..) and not with frame dropping (which would likely result in a visually perfect image with hitching, followed by a sudden sync loss as the monitor refuses to accept signals at a certain level). Additionally, it would require that the hardware designers for the chips inside the monitor had introduced frame-dropping behaviour at a refresh rate somewhere around 85Hz or so; considering that *absolutely all* LCDs to implement frame-dropping (which is caused by the scalers) do so at 60Hz, this seems to be pretty unlikely to me. As extra justification, checking the datasheets for the chips used in the monitor (the DVI-LVDS converter and the T-con controller) makes no mention of such a feature.
Your assumptions are based on flawed information, your claims are unfounded and your logic is unsound. All evidence indicates that the monitors work at high refresh rate as assumed, and continue to work all the way up to the point where they start glitching or desync. If you're going to make any more posts about this, please take the time to research the subject before acting like an expert on it.
PS: Also, it would probably be better if we avoid mentioning HDMI Type-B; the standard, for all intents and purposes, does not actually exist and is thus not relevant in any way. Last time I tried to look for a picture of the connectors the only thing I could find were sketches; nobody's actually built anything that conforms to it. As an aside though, the numbers you indicate for the bandwidth of HDMI Type-B (a non-clock limited cable electrically equivalent to DVI dual-link) are probably a lot closer to the actual limits of a dual-link DVI than any other numbers you referenced.
Originally Posted by Sxcerino
Have you noticed any response time lag with these monitors?
Coming from a S23A750D, I'm afraid that the lag is going to drive me nuts.
60-> 100hz is a 68% improvement, but if we think of it as the glass being half empty, it's also true that we're missing out on 32% of potential improvement over 60hz
The monitors have no scaler, and overall have a very clean path from the graphics card to the panel with no extra delays. They thus have very low input lag already, and higher refresh rates improve the situation even further. If input lag is your concern, these monitors are great performers. Response times however are obviously not as good as TN so ghosting can still occur - but you will get information on screen from your inputs as soon as possible.Edited by siberx - 4/17/12 at 8:23am