4K HDMI cables (are nonsense) (via Cnet)


HDMI.org / by Geoffrey Morrison

With the slow and inevitable transition to Ultra HD 4K happening whether it’s necessary or not, it’s not surprising that cable manufacturers are jumping at the chance to sell new and more expensive “4K” HDMI cables.

But guess what — you don’t need 4K HDMI cables, because your current HDMI ones can probably do 4K just fine. Seriously.

Here’s why.

In case you missed the tetralogy on HDMI cables, check out Why all HDMI cables are the same, Why all HDMI cables are the same, Part 2, Still more reasons why all HDMI cables are the same, and the HDMI Cable Buying Guide.

You’d think I’d have said my piece by now, but apparently not. Here’s the short version. There are only four kinds of HDMI cables:

High-speed with Ethernet
High-speed without Ethernet
Standard-speed with Ethernet
Standard-speed without Ethernet

 There’s no reason to get standard-speed cables anymore, as the price difference is negligible between those and the high-speed versions. As per the current HDMI 1.4 spec, in order for an HDMI cable to be considered high-speed, it must be able to pass 3,840×2,160 pixels at up to 30 frames per second (and 4,096×2,160 at 24 frames per second).

This means that even the cheapest high-speed HDMI cable can pass the maximum resolution possible with the current generation of Ultra HD 4K TVs.

And guess what — this isn’t just numbers on a page, or theoretical knowledge. I reviewed one of the first 4K TVs and plugged in a $2.50 HDMI cable between it and a 4K source. Guess what? It worked perfectly. So did the cheap HDMI cable Senior Editor David Katzmaier used in his review. I also used a 40-foot HDMI cable (with RedMere) that worked perfectly.

Since 3,840×2,160/30 is the maximum in the current HDMI spec, it doesn’t matter if you have a cable that’s capable of 10 times that. The sending and receiving chips (in the source and the TV, respectively) are only capable of 3,840×2,160/30. So you could set your PC to 10,000×10,000-pixel resolution, and even if the cable could support that bandwidth, the video card’s HDMI output chip couldn’t output it, and the display’s HDMI input chip couldn’t accept it.

In other words, it’s a chain, and all parts of the chain have to have the ability to support all the data. And right now, if the cable is rated high-speed, it can pass all the resolution currently possible with Ultra HD.