Skip to main content

HDMI 2.1 Cables Are About to Get Longer, a Lot Longer

HDMI
(Image credit: Shutterstock)

The HDMI Forum has added a new feature to the HDMI 2.1a specification called HDMI Cable Power (opens in new tab). In a nutshell, HDMI Cable Power allows active HDMI cables to draw power directly from the source rather than requiring a separate power cable.

Distance is the biggest enemy for HDMI cables, so you start to suffer from signal degradation at longer lengths. That's why passive HDMI cables are typically short and acceptable for most mainstream use. However, in those unique scenarios where you need to connect two devices over long distances, you have no choice but to opt for an active HDMI cable. These cables come with a small onboard processor that amplifies the signal. But, of course, the processor needs power, which it draws from both ends of the cable through a USB connector. Some active HDMI cables even come with a power adapter. The latest HDMI Cable Power technology aims to eliminate all this cable clutter.

A typical HDMI cable accommodates up to 50 mA in terms of power. With HDMI Cable Power, the cable can pull up to 300 mA at 5V. The feature increases the power draw by sixfold and doesn't need external connectors.

HDMI 2.1 flaunts higher bandwidth and drives resolutions up to 10K. Where HDMI 2.0 offers a maximum transmission of 18 Gbps, HDMI 2.1 boasts an impressive transmission bit rate of 48 Gbps — that's almost three times as much bandwidth. Currently, passive HDMI 2.1 cables go up to three meters. During the UHS Cable program testing phase, HDMI Forum expected passive cables to max out at five meters. HDMI Cable Power will open the doors to longer passive cables without the need for external power. 

However, there are some caveats. The HDMI cables and the source device need to support the HDMI Cable Power feature to ensure proper operation. While the connection remains the same, the cables are unidirectional. In other words, one end connects specifically to the HDMI source (transmitting) device, while the other goes to the HDMI Sink (receiving) device. If you connect the cable incorrectly, there is no harm — it just won't work.

New HDMI cables with native HDMI Cable Power support will come with a separate power connector for those source devices that don't support the feature. As we've seen before, the connectors will either take the shape of a USB Micro-B or USB Type-C port.

Pricing is one of the problems with active HDMI cables. They usually cost substantially more than their passive counterparts due to the added circuitry like chips and retimers. However, cables with HDMI Cable Power should cost less than your standard active cable in a perfect world.

Zhiye Liu
Zhiye Liu

Zhiye Liu is a Freelance News Writer at Tom’s Hardware US. Although he loves everything that’s hardware, he has a soft spot for CPUs, GPUs, and RAM.

  • WrongRookie
    I don't get it. Why does it matter how much power it can take when all it will do is provide 1080p at max?

    Wouldn't display ports still be a better option?
    Reply
  • JarredWaltonGPU
    WrongRookie said:
    I don't get it. Why does it matter how much power it can take when all it will do is provide 1080p at max?

    Wouldn't display ports still be a better option?
    HDMI 2.0 already drives 4K at 60Hz and 8K at 30Hz with 4:2:0 chroma subsampling. HDMI 2.1 will drive 4K at 144Hz, 8K at 30Hz, and 8K at 120Hz with Display Stream Compression. It can also do 10K, probably 60Hz with DSC.
    Reply
  • TheDukeofCool
    Admin said:
    HDMI Forum has announced the new HDMI Cable Power feature to allow for longer HDMI active cables that don’t require a separate power cable.

    HDMI 2.1 Cables Are About To Get Longer, A Lot Longer : Read more
    Why not just go with the new fiber HDMI cables? No need for additional power and, cable lengths as long as you need. They work perfectly for me as I keep my receiver 100 feet away out in my garage. No issues. They support 4k 120 / 8k / VRR / eARC, etc...
    Reply
  • edzieba
    TheDukeofCool said:
    Why not just go with the new fiber HDMI cables? No need for additional power and, cable lengths as long as you need. They work perfectly for me as I keep my receiver 100 feet away out in my garage. No issues. They support 4k 120 / 8k / VRR / eARC, etc...
    A media-changer from copper to fibre at either end would also need cable power, which is what this spec provides.
    Reply
  • RaunchyButts
    WrongRookie said:
    Wouldn't display ports still be a better option?

    Yes, DisplayPort would be a better option. Everything should have switched to DisplayPort years ago. HDMI was designed for CRTs, and it's becoming a band-aided mess like USB. Look at this:

    "the cables are unidirectional"

    Then they are a design failure. Period.
    Reply
  • mac_angel
    TheDukeofCool said:
    Why not just go with the new fiber HDMI cables? No need for additional power and, cable lengths as long as you need. They work perfectly for me as I keep my receiver 100 feet away out in my garage. No issues. They support 4k 120 / 8k / VRR / eARC, etc...
    I was going to ask the same. I'm confused at why there is no mention about hybrid HDMI cables.
    Also confused at why people are giving their opinions about it without trying to use a Google search first. Even Amazon has SO many versions of the hybrid cables. None needing external power. I have one myself.
    Reply
  • pixelpusher220
    RaunchyButts said:
    "the cables are unidirectional"

    Then they are a design failure. Period.
    My investments in call support centers may just pay off yet...hold on Dad's on the other line
    Reply
  • countmackula
    Admin said:
    HDMI Forum has announced the new HDMI Cable Power feature to allow for longer HDMI active cables that don’t require a separate power cable.

    HDMI 2.1 Cables Are About To Get Longer, A Lot Longer : Read more
    This would be a more exciting feature if my AV receiver could send enough power over the HDMI ARC output to my TV to power the TV to eliminate needing an electrical outlet and power cord up near the TV.
    Reply
  • hotaru.hino
    WrongRookie said:
    I don't get it. Why does it matter how much power it can take when all it will do is provide 1080p at max?

    Wouldn't display ports still be a better option?
    DisplayPort is a royalty-free standard controlled by a US-based standards organization.

    HDMI requires royalty to use and is controlled by a large conglomeration of companies involved in multimedia.

    If you were a for-profit company who not only makes TVs, but is also in this conglomeration, which sounds better?

    TheDukeofCool said:
    Why not just go with the new fiber HDMI cables? No need for additional power and, cable lengths as long as you need. They work perfectly for me as I keep my receiver 100 feet away out in my garage. No issues. They support 4k 120 / 8k / VRR / eARC, etc...
    Aside from needing copper to fiber, fiber has its own set of problems to overcome at the PHY layer. One could argue it's why optical SPDIF never really got an upgrade.
    Reply
  • Gavin Greenwalt
    edzieba said:
    A media-changer from copper to fibre at either end would also need cable power, which is what this spec provides.
    There's already enough power. There are loads of active fiber cables. Even some that are XBox certified for 4k 120hz.
    Reply