Originally Posted by zinfinion
DP 1.2 is not restrained by 400MHz RAMDACs so the full 540MHz pixel clock can be utilized. As far as the DP 1.2 spec is concerned, 4K @ 60Hz should be possible, whether the card or TV have any snafus that mess it up is another issue
What I am reading from these links, is that this first wave of 4K displays are faking it, and are actually split into two logical displays (even though physically it is one contiguous display), which is what is borking everything up.
When "real" 4K displays that are addressed as a single logical entity arrive, DP 1.2 will handle it just fine. And by that time HDMI 2.0 will likely be out, so it will be a moot point.tl;dr:
The blame lies with these split displays, not with the DP 1.2 spec or the DP 1.2 capable video cards.
So Nvidia GPUs like the GTX Titan don't restrict their DP 1.2 output with a 400mhz pixel clock? Because I can't find anything confirming that. I know the DP 1.2 cable and standard isn't restricted to 400mhz but as far am I've been aware Nvidia GPUs display outputs are restricted (via drivers?) and each single display output is limited to 400mhz, hence the problem even if we did have monitors that would accept the single input.
Would love clarification on this. Because a few of us were searching for information on it a few weeks back and couldn't find anything to confirm it other than a few hacks to bypass it but to what extent we weren't sure because we obviously don't have 4K monitors that's will accept a single DP 1.2 input of 4K at 60hz and can't test it.
All we know is it doesn't look good so far for single inputs and simply saying this new monitor will have it or 'its easily fixed in theory' doesn't cut it until the fix exists and is confirmed. Because two monitor surround should be easy to implement yet we still don't have it and won't for a while. Same with Windows 8 desktop windowed and fullscreen surround support. Something else that should be easy to fix/implement with surround but we don't have.
Originally Posted by xoleras
Hmm,. Modern GPUs do not even require the use of a RAMDAC, so i'm quite confused. The RAMDAC is a legacy item that converts digital to analog? This is a legacy item required for VGA analog output. If you're using a completely digital interface, the RAMDAC is not even used - It (DAC) is built into the graphics chip (AFAIK) but it is worthless to completely digital signals such as DVI, HDMI, and displayport.
All of the current 4k screens are HDMI and aren't HDMI 2.0, therefore there are issues associated with that. As mentioned, asus states that 1 displayport cable will do the trick for 4k @ 60hz - some GPUs may need BIOS updates or newer drivers, but it will be possible to drive them at 60hz. Some older GPUs may not be compatible, but as far as i'm aware all relatively recent cards will be fine with updated drivers. We just need proper PC monitors with DP and not HDTV's.
It has become pretty clear to me that the early adopters of 4k are getting the shaft. If anyone is buying a 4k screen, it's advisable to not do so until they have full HDMI 2.0 connectivity. We, alternatively, have another option not involving HDMI.
You blow a fuse and then pretend like it didn't happen?