displayport active versus passive with 4k

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kandor

Gawd
Joined
Aug 24, 2005
Messages
632
Hi,

I have a quadro k4000 card. This card has a dvi and 2 dp1.2 outputs. I bought a 4k monitor which is HDMI, so I also bought a dp to hdmi adapter. When I plug it in, the nvidia cp shows available resolution only up to 1080p. I know other people with the same monitor who used a dvi to hdmi adapter and have no problem getting 4k res.

I read that an active adapter is necessary in my case but I don't really understand why. I know the active adapter generates a clock signal, but why doesn't my friend with the dvi-hdmi adapter need an active one?

Or is there something wrong software wise?

Thanks,
 
Basically: you answered your own question there. passive adapters are limited to 1920x1200 or so.
DVI to HDMI works due to DVI and HDMI effectively being one in the same* so the card can talk full HDMI 1.4 which can drive 4k at 30hz or so.

*same signaling for video, HDMI can carry extra stuff is all. (audio, ethernet, etc..)
 
Cool, thanks for the info, now at least I know I'm not wasting money on this active adapter. I don't know enough about displayports but they seem from the outside to be second class if only for this reason.

*edit: Geez, I just read this on wikipedia. Way to make it perfectly clear! :)

'The DisplayPort signal is not compatible with DVI or HDMI. However, Dual-Mode DisplayPorts are designed to transmit a single-link DVI or HDMI 1.2/1.4 protocol across the interface through the use of an external passive adapter that selects the desired signal and converts the electrical signaling from LVDS to TMDS. Analog VGA and dual-link DVI require powered active adapters to convert the protocol and signal levels, and do not rely on Dual-Mode. VGA adapters are powered by the DisplayPort connector, while dual-link DVI adapters may rely on an external power source (see compatibility with HDMI, DVI and VGA).[9]'
 
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