Quick answer: There is no DisplayPort 1.5 specification. VESA went from 1.4a to 2.0, then renamed 2.0 to 2.1 and added UHBR10, UHBR13.5 and UHBR20 rates. If a listing advertises 1.5, it is either a mislabelled 1.4 cable or marketing for an unannounced product; buy on the UHBR rating instead.
The confusion is understandable. Version numbers used to track bandwidth in a straight line, and a monitor advertised as 1.5 would suggest something between 32.4 and 80 Gbit/s. VESA broke that pattern when it moved to transport rates and then dropped the minor version entirely, so the number on the box stopped being a reliable guide.
What the versions really deliver
| Version | Rate | Raw bandwidth | Practical mode |
|---|
| 1.2 | HBR2 | 21.6 Gbit/s | 4K60 8 bit 4:4:4 |
| 1.4 and 1.4a | HBR3 | 32.4 Gbit/s | 4K120 8 bit, 8K60 with DSC |
| 2.0 and 2.1 | UHBR10 | 40 Gbit/s | 4K144 10 bit |
| 2.1 | UHBR13.5 | 54 Gbit/s | 5K120, dual 4K144 |
| 2.1 | UHBR20 | 80 Gbit/s | 8K60 10 bit, 4K240 |
Display Stream Compression changes the arithmetic. With DSC, which is visually lossless at 3:1, a 1.4 link can carry 8K60 and a UHBR10 link can carry dual 4K144. Many monitors rely on DSC to reach their headline numbers, which is why two displays with the same resolution can need very different cables.
Why the label on the box is unreliable
Cable certification names
VESA certifies cables as DP40 for UHBR10 and DP80 for UHBR20, and DP80LL for the active long length variant that reaches about 3 m. A cable sold as 1.5 has no certification path, because no such test exists. Check for the DP40 or DP80 mark, and for passive copper, assume 2 m is the reliable limit at UHBR20.
Monitor firmware and link training
A UHBR20 capable monitor may still come up at HBR3 if link training fails. The cause is usually cable loss or a port that shares lanes with a second output. Checking the monitor’s on screen display for the negotiated rate tells you more than any label: it will show HBR3, UHBR10 or UHBR20 explicitly.
What to buy for a given monitor
For 1440p at 165 Hz, HBR3 is sufficient and a certified 1.4 cable is the correct purchase. For 4K at 144 Hz with 10 bit colour and no compression, UHBR10 is required, which means a DP40 cable and a GPU that exposes the rate. For 8K at 60 Hz, either 1.4a with DSC or UHBR20 without it will work, and the cheaper path is often the compressed one. Buying a DP80 cable for a 1440p monitor wastes money but does no harm; buying a 1.4 cable for a UHBR20 monitor produces a monitor that quietly runs at half its capability.
MST, daisy chains and lane allocation
Multi stream transport lets one link carry several independent displays. The hub splits the available payload, not the raw bandwidth: two 4K60 streams at 8 bit need about 25 Gbit/s together, which fits HBR3 only with compression. That is why a second monitor sometimes forces both to a lower refresh rate rather than failing outright.
Daisy chaining needs a monitor with a DisplayPort output, and the last monitor in the chain terminates the stream. Each hop adds a small amount of latency and consumes link margin, so three displays in a chain is the practical limit on copper at UHBR rates. A hub with its own power supply behaves better than a chain when the displays are large.
What the monitor reports versus what the box says
The on screen display of a monitor usually has an information page that lists the negotiated link rate and lane count. That page is the only trustworthy source of truth in a dispute about a cable, because it reflects what the two ends actually trained at rather than what the packaging promised. A monitor showing HBR3 when the cable is sold as UHBR20 has either a firmware cap or a cable that cannot hold the rate.
Update the display firmware before replacing hardware. Several monitors shipped with an early firmware that trained at HBR3 on UHBR capable ports, and a firmware update restored the higher rate without any change to the cable.
Practical scenarios
- Ultrawide 5120 x 1440 at 120 Hz: HBR3 with DSC works; without DSC the same panel needs UHBR10, so confirm the monitor’s DSC support before choosing the cable.
- Two 4K60 monitors on one port: MST shares the link, so each stream gets half the bandwidth; a UHBR10 link keeps both at 4K60 without subsampling.
- Laptop with USB-C Alt Mode: the port carries four DisplayPort lanes, so the cable must be rated for the rate the GPU exposes, not for the connector shape.
- Long run to a wall mounted display: use a DP80LL active cable up to about 3 m, and beyond that an optical DisplayPort extender, because passive copper will not train at UHBR20.
FAQ
Is DisplayPort 1.5 coming?
VESA has not published a 1.5 specification, and the naming scheme moved to 2.x with UHBR rates. Any product page citing 1.5 should be treated as a typo or a placeholder, and the actual capability confirmed from the UHBR rating or the monitor’s reported link rate.
Is a 1.4 cable compatible with a 2.1 monitor?
Yes, the connector and protocol are backward compatible, but the link will train at HBR3 and cap at 32.4 Gbit/s. You lose the higher refresh rates unless DSC covers the difference.
Does DisplayPort carry audio?
Yes, up to eight channels of PCM or compressed bitstreams, embedded in the same stream. There is no audio return channel, so a monitor cannot send audio back to the source the way HDMI eARC can.
Next step
Buy by rate, not by number: DisplayPort 1.4 cable covers HBR3, DisplayPort 2.1 cable covers UHBR, and DisplayPort cable for gaming covers high refresh displays. Tell us the monitor model and refresh rate at zongcarrie@zh-zong.com or +86 13543026126 and we will confirm the rate you need.
