4K or UltraHD Displays and Your PC

4K, or UltraHD refers to a class of high-definition displays and video. The term 4K references the horizontal resolution of the picture, typically either 3840 pixels by 2160 pixels or 4096 pixels by 2160 pixels. This capability is roughly four times the resolution of the current HD standards that top out at 1920 pixels by 1080 pixels. While 4K computer monitors are becoming commonplace, achieving true UltraHD on any PC requires significant hardware upgrades.

Video Bandwidth and Connections on Computers

Computers face a problem rendering 4K or UHD content. The extremely high resolutions require a large amount of bandwidth in order to transmit the increased size of the video data. Older computer video technologies, such as VGA and DVI, lack the bandwidth and therefore can't deliver those resolutions reliably. To maintain 4K resolution, you need newer video connectors such as HDMI, DisplayPort, and Thunderbolt 2 or 3.

Most consumer electronics support HDMI, which gives it an advantage for adoption by the computer display market. A video card with an HDMI port is required, as well as HDMI high-speed-rated cables.

Many computer displays and video cards use the DisplayPort technology, though it is less familiar to the average user. The DisplayPort v1.2 specification runs the full 4K UHD video signal up to 4096 pixels by 2160 pixels at 60 frames per second.

Refresh Rate

HDMI signals commonly transmit with a 30Hz refresh rate, or 30 frames per second. This rate works for watching movies on a television, but for computer gamers, such low frame rates cause serious eye strain. Gamers prefer 60 fps refresh rates or higher for more fluid movement on the screen.

Video Card Performance

Every graphics processor handles basic video rendering at the 4K UHD resolutions, but fast-paced 3D video games presented in 4K require significant graphics processing power. At four times the resolution of standard high definition, four times the amount of data must be processed by the graphics card.

The processing load these cards handle produces significant heat inside a system, which requires greater cooling capabilities. This all comes with a higher price tag. Running several monitors with 4K resolutions vastly increases the demands on bandwidth and processing power.

Video CODECs

Streaming and downloading 4K videos present additional challenges. The size increase in the data stream requires additional internet traffic even as typical sizes of video files has also increased.

Most high-definition video uses the H.264 video codec from the Moving Picture Experts Group, rendering MPEG4 video files. This codec has been an efficient means of encoding data, but with 4K UHD video, a Blu-ray disc can hold only one-quarter of the video length. The subsequent H.265, or High-Efficiency Video Codec, further reduces data sizes.

Older video hardware has been hardcoded to use the H.264 video to be as efficient as possible. The same is true for many graphics solutions found in mobile products. Some of the adaptation necessary for 4K can be handled through software, but many older mobile products like smartphones and tablets may not be able to play the new video format.