Don't fall for the 4k HDMI cable sales gimmicks. Know what you are paying for.
With all the talk about 4k Televisions how important are those pricey 4k HDMI cables? Honestly all the hype about 4k cables is not what it seems. HDMI stands for High Definition Media Interface and come in HDMI 1.0, 1.1, 1.2, 1.2a, 1.3, 1.3a, 1.3b, 1.3b1, 1.3c, 1.4, 1.4a, 1.4b, 2.0, and the latest version, 2.1. Most cables made within the last few years are going to be HDMI 2.0 which means it will work for 4k TV's. HDMI 2.0 was released on September 4, 2013. No need to purchase a special 'Monster HDMI cable' and overpay for basically the same thing. You just want HDMI 2.0 or higher to provide you with the faster 60Hz frame rate. These cables should not run you more than $25 for a 15 foot cable. If you are paying more you are overpaying.
HDMI 2.0 offers a few key upgrades from older cables. First off it enables transmission of HDR (High Dynamic Range) video, 60Hz refresh rate. Higher Bandwidths up to 18 gigs per second ! 4k is 4 times the clarity of a standard 1080p video resolution. The audio has been upgraded as well. HDMI 2.0 supports up to 32 audio channels for a much better audio experience. It supports up to 1536kHz for ultra crisp audio.
HDMI 2.0 also offers ARC (Audio Return Channel) which was original introduced with HDMI 1.4. Basically this allows you to wire your TV to your stereo or surround sound receiver and all your devices will be in surround sound, or play through your soundbar. No need to connect each device to your soundbar or receiver , as long as the ARC is used and your setup done properly everything should be in surround sound. This will include your cable box, satellite, DVD or Blu-Ray player, even your gaming console. Also anything you watch on your TV's 'Smart Hub' such as Netflix, Amazon Prime, or Hulu should also be in surround. This will allow for 4 audio steams and up to 32 channels, which will provide the greatest quality for your 'Dolby ATMOS' enabled system. If you are using HDMI 2.0 or high you will have twice the frames per second as older HDMI cables, jumping from 30 FPS, to 60fps. It will still support 3D, and Ethernet channels, but just at greater speeds and 21:9 aspect ratio instead of just offering 16:9. Imagine for a moment that picture you took has 4x zoom, but still looks the same size. More pixels per square inch, deeper colors, richer resolution. Older HDMI 1.4 cables will give you a 4k signal but at lower frames per second (24-30fps) which will make media broadcasted in 60 fps choppy and not as smooth. In short when you buy a 4k TV check to make sure it will support HDMI 2.0, and not just 1.4, and that your HDMI cables are HDMI 2.0. They are both 4k, but HDMI 1.4 is an older technology, with less frame per second. Most services are just now starting to offer 4k programming with the exception of some streaming services that have been offering the increased bandwidth for a couple of years now. 8K TV's are now starting to become available, but just like 1080p HD, and 4k it will take the market a little while to catch up to the technology.
More information can be found here.