The live version of this guide is available on the LinusTechTips forum here. This page was only created for code testing and is no longer used, so the information here has not been updated in several years.

Please use the up-to-date version on the forum: https://linustechtips.com/topic/729232-guide-to-display-cables-adapters-v2/

How to use:
  • Use the output (left) dropdown only, for general information about an interface (DVI, HDMI, etc.)
  • Use the input (right) dropdown only, to see all options for connecting to a specific port on a display
  • Use both dropdowns for information about a specific adapter combination — make sure they are in the right order!
  Output
(Computer / Source) 		  Input
(Monitor / TV / Display) 		 
   
(Note: Order matters! Make sure that the Output / Input are in the correct order and not reversed.)
 
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› Maximum Refresh Frequency and Resolution of Everything [Link]
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› Which Cable Type Should I Use? (DisplayPort vs. HDMI vs. DVI vs. VGA) [Link]
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› Connecting to a 120+ Hz Display [Link]
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› Active vs. Passive Adapters [Link]
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› Active Adapter Requirements for Multi-Monitor Configurations [Link]
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› Do HDMI Cables Have Versions? [Link]
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› Is HDMI Limited to 60 Hz? [Link]
Is HDMI Limited to 60 Hz?

No, HDMI is not limited to 60 Hz. Only HDMI 1.0 and 1.1 were restricted to specific formats (which were all 60 Hz and under), but this restriction was removed in HDMI 1.2 (§6.1) all the way back in 2005, and HDMI has not had any hard limit on refresh frequency since then. 720p 120 Hz is in fact explicitly listed in HDMI 1.2 as a supported format (§6.3.2), although at 1080p it was still limited to ≈60 Hz by bandwidth constraints. HDMI 1.3 in 2006 alleviated these bandwidth constraints, increasing it to surpass Dual-Link DVI, and display makers have been free to implement 1080p 144 Hz over HDMI ever since then.

But I have an ASUS VG248QE / BenQ XL2411Z / Acer GN246HL and it's capped at 60 Hz over HDMI!

Yes; these and many other 1080p 144 Hz monitors are equipped with HDMI 1.4a inputs, yet are still limited to 60 Hz over HDMI. This is just an unfortunate limitation of those particular monitors, it is not a limitation of the HDMI standard. Other monitors, such as the ViewSonic XG2401, the Nixeus NX-VUE24A, and the Samsung C24FG70 are also 1080p 144 Hz monitors with HDMI 1.4a ports, and they do accept 1080p 120/144 Hz over HDMI. It's purely a matter of manufacturer's discretion whether they want to implement that capability or not. Sadly, many instead choose to implement HDMI 1.4a with reduced bandwidth, presumably for cost-saving reasons.

The long and short of it is, some displays support 1080p 120+ Hz over HDMI 1.4, and some don't. It just depends on the display, so you'll need to do some research on whatever product you're considering.

But if a product doesn't support the full bandwidth of HDMI 1.4a, surely it can't be HDMI 1.4a-compliant!

Unfortunately it still can. Support for the full bandwidth is not a requirement for a device or control chip to be HDMI 1.4a-compliant. Very few displays (certainly during the peak years of HDMI 1.3/1.4) have specs that can even use the full bandwidth, so it wouldn't make sense to require that all devices wishing to implement any HDMI 1.4 features must use a more expensive control chip capable of the full bandwidth, when virtually none of them have any use for it.

Isn't the extra bandwidth in 1.4 only used for 3D at 60 Hz per eye, not for normal 120 Hz video?

No. This is something that people often repeat for some reason, that although 1080p 60 Hz uses less than half the bandwidth provided by HDMI 1.4, that extra bandwidth is apparently only allowed to be used for 3D frame packing. While it is true that 3D is one of the uses for the extra bandwidth, there is no restriction on using it for other purposes, such as standard video transmission at higher resolutions and refresh frequencies. This claim that the extra bandwidth is only allowed to be used for 3D is a bit of a head scratcher when you consider that the bandwidth increase has been there since HDMI 1.3, but the 3D format definitions (such as frame packing) weren't added until HDMI 1.4.

But if you do meet anyone who insists that the extra bandwidth really is only allowed to be used for 3D, please feel free to ask them which page or section of the HDMI Specification establishes this supposed restriction, I'd be interested to find out. I've never had an answer.

Wasn't support for 1080p 120 Hz only added in HDMI 1.4b (and therefore not supported in 1.4a and earlier)?

No. This claim comes from people reading it on Wikipedia but not checking the citation, which was just a youtube video of some random guy saying so. Speaking as someone who has the actual HDMI 1.4/a/b Specification documents on hand, this claim of 1080p 120 Hz support being introduced in HDMI 1.4b is completely false. Nothing was introduced in HDMI 1.4b (see here), simply minor edits and clarifications to the document itself, which is why you don't generally see "HDMI 1.4b" devices, because technologically it is identical to HDMI 1.4a, just some changes to the wording in the HDMI Specification document.

1080p 120 Hz has been explicitly listed in the HDMI Specification as a supported format since HDMI 1.4 (§6.3.2), not 1.4b, but even prior to that in HDMI 1.3 or 1.3a it can be implemented as a vendor-specific format which is a perfectly valid approach. Video formats do not require "support" from the HDMI Specification to work, because the word "support" does not mean what most people think it means in this case.

When the HDMI Specification "adds support" for a certain format, it doesn't mean it in the conventional sense of "adding the capability" as if it wasn't previously possible. They mean it in a more literal sense of adding supporting material to help strengthen it, by defining standardized timings for the format to help with compatibility and ease of implementation instead of leaving it purely to the vendor's discretion.

This "support" isn't actually necessary to display a format though. Even if a format isn't supported by the HDMI Specification, it can still be displayed through HDMI. 2560×1440 for example is not listed in the HDMI Specification either, so it is just as "unsupported" by HDMI as 1080p 144 Hz is, and yet it's implemented over HDMI on hundreds of different monitors. The same can be done with 1080p 144 Hz if manufacturers choose to do so, and they have done so on several monitors as mentioned above.

Another example of this usage of the term "support" is ultrawide formats; HDMI 2.0 "added support" for the 21:9 ratio, even though ultrawide resolutions were available before HDMI 2.0 even existed and were working just fine over HDMI 1.4a. "Adding support" for 21:9 just meant the HDMI 2.0 spec added material to help establish standardized formats and timings, not that 21:9 formats weren't possible in previous versions, and indeed the majority of ultrawide monitors still use HDMI 1.4a even though it "doesn't support" 21:9 ratio formats, because it doesn't need to.

Just because "HDMI doesn't support X", this does not mean "HDMI doesn't allow X" or "X won't work over HDMI".

Citation Needed!!!

Here's the first sentence of the video section of the HDMI 1.4a Specification:

HDMI Specification Version 1.4a (2010), §6.1

6.1  Overview

HDMI allows any video format timing to be transmitted and displayed. To maximize interoperability between products, common DTV formats have been defined. These video format timings define the pixel and line counts and timing, synchronization pulse positions and duration, and whether the format is interlaced or progressive. HDMI also allows vendor-specific formats to be used.

"Any video format timing". Am I just taking it out of context and applying it beyond its intended meaning? No. Here's the same section from HDMI 1.1:

HDMI Specification Version 1.1 (2004), §6.1

6.1  Overview

HDMI allows a wide variety of explicity defined video format timings to be transmitted and displayed. These video format timings define the pixel and line counts and timing, synchronization pulse positions and duration, and whether the format is interlaced or progressive.

In HDMI 1.0 and 1.1, only certain pre-defined formats were allowed (listed in §6.1–6.3; all of them are 60 Hz and under, so HDMI was indirectly limited to 60 Hz by that). In 2005 with the release of HDMI 1.2, that clause was specifically changed to say what it still says today, that any format is allowed. It's quite deliberate.

HDMI 1.2 was designed to make HDMI more viable for the PC space, by allowing any arbitrary resolution and refresh rate (within the bandwidth limit), as opposed to the strict adherence to only standardized home theater formats required by HDMI 1.0 and 1.1. Although it does still have a list of pre-defined formats (to maximize interoperability between products, as it says), any format which is not explicitly defined in the HDMI Specification may still be implemented as a vendor-specific format.

HDMI 1.2 also expanded the list of explicitly defined formats itself to include some >60 Hz formats like 720p 120 Hz, so the claim that it or later versions of HDMI impose a flat 60 Hz limit is pure nonsense.

HDMI Specification Version 1.2 (2005), §6.3.2

6.3.2  Secondary Video Format Timings
  • 720(1440)x240p @ 59.94/60Hz
  • 2880x480i @ 59.94/60Hz
  • [...]
  • 1920x1080i @ 119.88/120Hz
  • 1280x720p @ 119.88/120Hz
  • 720(1440)x480i @ 239.76/240Hz
  • 720x480p @ 239.76/240Hz

However, the maximum bandwidth of HDMI 1.2 was the same as 1.0 and 1.1, so at 1080p it was still limited to 60 Hz due to bandwidth constraints.

In 2006, HDMI 1.3 increased the maximum bandwidth by over double, enough for up to 144 Hz at 1080p. From this point onwards display manufacturers have been free to implement 1080p 120/144 Hz as a vendor-specific format.

HDMI 1.4 added 1080p 120 Hz to the list of explicitly defined formats, so it is no longer even necessary for the manufacturer to have to define their own timings for the format:

HDMI Specification Version 1.4 (2009), §6.3.2

6.3.2  Secondary Video Format Timings
  • 720(1440)x240p @ 59.94/60Hz
  • 2880x480i @ 59.94/60Hz
  • [...]
  • 1920x1080p @ 119.88/120Hz
  • 1920x1080p @ 100Hz

As for 1080p 144 Hz, as before, manufacturers are still free to implement it as a vendor-specific format, and some have done so already.

If a 1080p 120+ Hz display doesn't support 120+ Hz over HDMI, it's the fault of that display model, not a limitation of the HDMI standard.
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