Nvidia 340.43 Driver Allows HDMI 1.4 To Output 60Hz 4K UHD

The HDMI specifications essentially limit the output of UHD (3840 x 2160) to 30Hz and 4K (4096 x 2160) to 24Hz. DisplayPort outputs are required to reach 60Hz at those resolutions or the use of dual HDMI ports. Over at Anandtech they have discovered that the dual HDMI requirement isn’t set in stone. Some users found out that using the 340.43 Nvidia drivers with Kepler based video cards allows UHD displays to be powered at 60Hz over a single HDMI. However, the new workaround is not present on all UHD displays, only some have implemented it. The workaround method effectively reduces the bandwidth required by the UHD 4K 60Hz stream by using chroma subsampling which effectively lowers the image quality and amount of chroma colour data. This frees up enough bandwidth to jump from 30 to 60Hz while maintaining a UHD resolution.

4:2:0 chroma sampling is only available on a handful of UHD 4K TVs currently on the market but Nvidia has confirmed their Kepler cards do support it. The UHD 60Hz signal is only really good for video output though, if you were hoping to use a 4:2:0 compatible UHD TV as a desktop monitor you will be disappointed. Currently, the 4:2:0 workaround is a cheap way of getting 60Hz UHD video but for a true UHD 60Hz image without quality loss Displayport 1.2 is the only way to achieve that until HDMI 2.0 UHD displays and TVs hit the market.

Source: Anandtech

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