DisplayPort 2.1 Explained

High resolutions such as 4K coupled with increasingly higher refresh rates and HDR, which requires 10-bit color, demand higher and higher bandwidth. While the currently dominant video interface in PC space, DisplayPort 1.4, is enough right now, it won’t be in the future. Enter DisplayPort 2.1.

Why DisplayPort 2.1 Matters

At the moment, the maximum refresh rate found on even the best 4K monitors is 240Hz. Add 10-bit color needed for HDR, and the total bandwidth for an uncompressed 4K@240Hz video signal with 10-bit color is almost 80Gbps!

If it weren’t for Display Stream Compression (DSC), a form of visually lossless compression (the difference in quality between uncompressed and compressed signal is unnoticeable by the human eye), 4K 240Hz monitors wouldn’t work with the most popular video interface in the PC space, DisplayPort 1.4, which tops out at 32.4Gbps.

With DSC, a 4K@240Hz video signal with 10-bit color tops out at just below 23Gbps. However, a 4K@360Hz video signal with 10-bit color uses 36.5Gbps of bandwidth with DSC, a markedly higher bandwidth than what DisplayPort 1.4 can offer. A similar situation is with, for example, 1440p resolution coupled with a 600Hz refresh rate and 10-bit color.

This is where DisplayPort 2.1 comes in. DP 2.1 is necessary so that future monitors can offer higher refresh rates and resolutions. Since manufacturers won’t suddenly stop developing display panels that can deliver higher refresh rates and resolutions (we’ve already got 1,000Hz monitors in the pipeline), DisplayPort 2.1 is required. Another reason why we need a faster DisplayPort standard is because DisplayPort is typically preferable over HDMI in PC monitors.

One Standard, Three Different Tiers

DisplayPort 2.1 features three different tiers, each having a different maximum bandwidth: UHBR10, UHBR13.5, and UHBR20.

UHBR stands for “Ultra-High-Bit-Rate,” with the numbers representing the maximum bandwidth per data lane. Since the DisplayPort standard supports four lanes, you can calculate the total bandwidth for each tier, in Gbps, by multiplying its number by four.

Note that the total bandwidth isn’t equal to the maximum data rate DisplayPort 2.1 tiers can actually deliver to a monitor. Since we have to account for encoding overhead and other redundancies, the maximum data rate of each tier is lower than its maximum bandwidth.

As you can see, even the slowest, UHBR10, DisplayPort 2.1 tier offers about 20% higher bandwidth than DisplayPort 1.4, allowing it to, for example, support 4K@240Hz resolution with 10-bit color and DSC, or 1440p@500Hz resolution with 10-bit color and DSC.

According to VESA (Video Electronics Standards Association), the governing body behind the DisplayPort standard, the maximum resolutions and refresh rates supported by DP 2.1 are:

• One 16K (15360×8460) display @60Hz and 4:4:4 HDR (with DSC)
• Two 8K (7680×4320) displays @120Hz and 4:4:4 HDR (with DSC)
• Three 10K (10240×4320) displays @60Hz and 4:4:4 HDR (with DSC)

Suffice it to say your multi-monitor needs will be covered.

DisplayPort 2.1 Issues

While DisplayPort 2.1 looks promising, it comes with several caveats.

The biggest one is that for a product to be DisplayPort 2.1 certified, it doesn’t, in fact, have to support any of the UHBR tiers. If you visit the VESA web page that contains the DisplayPort 2.1 specification announcement, you can find the following statement:

“Due to this effort, all previously certified DisplayPort 2.0 products including UHBR (Ultra-high Bit Rate) capable products – whether GPUs, docking station chips, monitor scalar chips, PHY repeater chips such as re-timers, or DP40/DP80 cables (including both passive and active, and using full-size DisplayPort, Mini DisplayPort or USB Type-C connectors) – have already been certified to the stricter DisplayPort 2.1 spec.”

As you can see, VESA has certified all DisplayPort 2.0 products (a previous DP standard that never saw practical implementation) to the DisplayPort 2.1 spec, including UHBR capable products. Which means that even DP 2.0 products that do not support UHBR have also been certified to DisplayPort 2.1. In other words, you have to be extra careful and check whether a DP 2.1-certified cable, monitor, or other product actually supports one of the three UHBR tiers. This is reminiscent of the fake HDMI 2.1 cables fiasco from a few years ago.

Luckily, VESA does include three DP 2.1 bandwidth labels that easily communicate the maximum data rate of a certain DP 2.1-certified cable. These are DP40, DP54, and DP80, with the number representing the max bandwidth in Gbps. So, if you plan to purchase a DP 2.1 cable, make sure it comes with one of the labels shown in the image below.

Remember that you shouldn’t just get any DP 2.1 cable supporting one of the three UHBR tiers; you also have to get one with enough bandwidth for your needs. For instance, if you get a monitor that requires more than 40Gbps of bandwidth to work at its native resolution and refresh rate combo, you’ll need at least a DP54 cable.

One example here is the Samsung Odyssey Neo G9 G95NC, which features a 7680×2160 resolution and 240Hz refresh rate. This monitor requires UHBR 13.5 to work at this resolution and refresh rate combo, meaning you’ll need a DP54 cable if you want to use the monitor at its native resolution and refresh rate.

The other issue with DisplayPort 2.1 is that only a couple of DP80 monitors are longer than 1.5 meters. If you need a longer DP80 cable, as of writing this writing, there are only four DP80 cables that are at least 1.8 meters long. The rest are either shorter or don’t include their length in the DP 2.1-certified cable database.

The final caveat is the fact that NVIDIA GPUs don’t support DP 2.1. This may change with RTX 5000 graphics cards, but at the moment, even the RTX 4090, the best GPU on the market, is limited to DP 1.4 bandwidth. On the other hand, AMD RDNA 3 GPUs support DP 2.1 UHBR 13.5. Lastly, the recently released Intel Arc B580 graphics card also supports DP 2.1 UHBR 13.5, which hints that other Intel Battlemage GPUs will support DP 2.1 as well.

With that said, exactly zero consumer-grade graphics cards support the highest, UHBR20 tier. In other words, until we get a GPU with DP 2.1 UHBR20 support, you won’t see any monitor offering the max resolution and refresh rate supported by DP 2.1, such as a 16K HDR monitor running at 60Hz.

The DisplayPort 2.1 standard is necessary because PC monitors are getting faster and faster refresh rates at higher and higher resolutions. The fact of the matter is that DisplayPort 1.4 simply doesn’t push enough bandwidth to support some of those combinations, such as a 4K@360hz with HDR support.

While DisplayPort 2.1 is still nascent, it’s only a matter of time before DP 2.1 becomes a requirement for high-end PC monitors. Let’s just hope that DisplayPort cable manufacturers will offer longer DP 2.1 cables; otherwise, keeping your PC on your desk next to your monitor won’t be just a fad, but a necessity (shudder…).