Originally Posted by galneon
Yeah, this would certainly be the first time I've heard of HDMI with audio (2-channel PCM or 8-channel, doesn't matter) passing 4:4:4 through the HDMI out of the 460. I'm also positive any card would pass 4:4:4 no problem from the DVI port. It's when audio from the HDMI port comes in to play that things go to crap :/ I agree with you totally.
Yeah, the HDMI->HDMI + Audio combination seems to be culprit for messing up 4:4:4 sampling capability. Here's what my experimentation shows...
About a month ago, while helping another ATI person try to get his 4:4:4 working, I had stated I got 4:4:4 working on HDMI->HDMI. However, in retrospect, I recall skipping the "ATI HDMI/DP Audio Driver" option when installing the Catalyst drivers. Thus the audio was never a factor and I was able to get 4:4:4 on HDMI->HDMI.
But since then, I've updated my Catalyst drivers and apparently also installed the HDMI/DP audio option. As I mentioned in an earlier post, I can no longer get 4:4:4 on HDMI->HDMI.
So I uninstalled Catalyst, ran Driver Sweeper, disconnected all video card ports except HDMI->HDMI, rebooted my computer, and installed Catalyst 10.12 -- but this time without the "ATI HDMI/DP Audio Driver" option. Rebooted again, and unfortunately still no 4:4:4 (even after cycling through all four Pixel Format options). But here's the really weird part... I disconnected the HDMI->HDMI connection and replaced it with a DVI->HDMI connection. 4:4:4 was there as expected. So then I disconnected DVI->HDMI, replaced it HDMI->HDMI, and 4:4:4 was now there in all its glory
While still on the HDMI->HDMI (w/ 4:4:4) connection, I rebooted my computer. Unfortunately, 4:4:4 was no longer there. So I repeated the DVI-HDMI / HDMI-HDMI swap again, but 4:4:4 never came back. I tried it again, and still 4:4:4 never came back.
So even with a HDMI->HDMI + No Audio connection, it seems 4:4:4 *is* possible, but getting it to happen is rare due to some unknown factor (for me anyways, your outcome might be different). As galneon theorizes in post #826, this issue could just be the nature of the HDMI hardware implementation of both video card vendors. And if that's the case, getting HDMI to output 4:4:4 without EDID hacks is probably impossible
On a different note, when you guys say "the ATI EDID fix", is this the same Nvidia EDID fix that nuker43 came up with? Or is it something different? I like to get my facts straight so I can update the FAQ accordingly.