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DisplayPort 2.1 is the better technical choice for extreme refresh rates when the graphics card and monitor both provide UHBR20. A UHBR20 connection has up to 77.37 Gbps of video payload, compared with about 42.6 Gbps for HDMI 2.1. That advantage does not make every DisplayPort 2.1 product faster: DP 2.1 also includes UHBR10 and UHBR13.5, and many 4K 240Hz modes on either interface rely on Display Stream Compression (DSC). Check the exact port tier, DSC behavior, color-depth limits, GPU output and cable certification before buying.
The direct answer
For a high-refresh monitor, choose the fastest interface that both devices actually implement. If your graphics card and monitor support DisplayPort 2.1 UHBR20, use it with a certified DP80 cable for the most uncompressed headroom. DisplayPort 2.1b UHBR20 provides an 80.0 Gbps link and a maximum 77.37 Gbps payload, substantially more than HDMI 2.1’s 48.0 Gbps link and approximately 42.6 Gbps payload.
HDMI 2.1 remains fully capable of many demanding modes. It is often the strongest common connection on television-style displays, game consoles and monitors that expose HDMI 2.1 but only an older or lower-tier DisplayPort implementation. At 4K and 240Hz, the visible result is determined by the complete system: resolution and timing, refresh rate, RGB or chroma format, 8-, 10- or 12-bit output, HDR, DSC support, variable-refresh implementation and firmware. A port label alone cannot establish the usable mode.
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What the bandwidth numbers actually mean
| Interface | Advertised link rate | Payload figure cited | What it means for a monitor |
|---|---|---|---|
| DisplayPort 2.1 UHBR20 | 80.0 Gbps | Up to 77.37 Gbps | Highest DisplayPort headroom; intended for uncompressed or less-compressed extreme modes when both endpoints support UHBR20. |
| DisplayPort 2.1 UHBR13.5 | 54.0 Gbps | Not stated in the supplied specifications | Faster than UHBR10, but below UHBR20; the monitor’s mode table determines whether DSC is needed. |
| DisplayPort 2.1 UHBR10 | 40.0 Gbps | Not stated in the supplied specifications | A genuine DP 2.1 implementation that can have less headroom than a high-end HDMI 2.1 implementation. |
| HDMI 2.1 | 48.0 Gbps | Approximately 42.6 Gbps | Enough for many high-refresh modes, generally with less margin than UHBR20 at the same color depth and timing. |
The link rate is the signaling speed before protocol overhead. Payload is the portion available for video data after that overhead, so payload is the more useful number when comparing whether a timing can fit without compression. Tom’s Hardware’s 2025 comparison lists 80.0 Gbps and 77.37 Gbps for DisplayPort 2.0/2.1 and 48.0 Gbps and approximately 42.6 Gbps for HDMI 2.1.
#1 Best Overall
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DisplayPort 2.1 is therefore a family of capability levels, not one guaranteed speed. VESA’s current FAQ gives the 77.37 Gbps maximum for DP 2.1b UHBR, while RTINGS has documented products marketed as DisplayPort 2.1 that use UHBR10. The words “DP 2.1” without the UHBR tier are incomplete information.
Why 4K 240Hz is a special case
A 3840×2160 image contains 8,294,400 active pixels. At 240 frames per second, the active image alone carries roughly 47.8 Gbps at 8-bit RGB and 59.7 Gbps at 10-bit RGB, before blanking intervals, transport overhead and HDR metadata. Those simple figures explain why a 4K 240Hz monitor can exceed HDMI 2.1’s approximately 42.6 Gbps payload and lower-tier DisplayPort implementations even though the connector appears compatible.
Real monitors use a selected timing, and the final transport requirement varies with blanking, color format and bit depth. A monitor may therefore offer 4K 240Hz only with DSC, only at 8-bit, only with a reduced-blanking timing, or only through one of its inputs. The same panel can expose different refresh-rate and HDR combinations on its DisplayPort and HDMI inputs.
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- Uncompressed RGB 4:4:4: Preserves full color detail and is preferred for desktop text, but has the highest bandwidth requirement.
- YCbCr 4:2:2 or 4:2:0: Reduces chroma bandwidth. It can make a mode fit, but colored text and fine UI elements may look softer.
- DSC: Compresses the stream in a visually lossless manner so a high-refresh RGB/HDR mode can fit through the link. The monitor and GPU must both support it.
For a desktop monitor, DSC is usually preferable to chroma subsampling because it preserves 4:4:4 text clarity. Whether DSC is available, selectable or transparent to the user is product-specific.
DisplayPort 2.1: verify the UHBR tier
UHBR10
UHBR10 is a 40.0 Gbps link. It is valid DisplayPort 2.1, but it is not equivalent to UHBR20 and may provide less practical margin than HDMI 2.1 for a particular 4K 240Hz, HDR and 10-bit combination. RTINGS’ product examples show why the tier must be checked rather than inferred from the generation number.
Rank #2
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UHBR13.5
UHBR13.5 raises the link to 54.0 Gbps. It sits between UHBR10 and UHBR20, so a monitor may support more high-refresh combinations without compression, while another may still use DSC for 4K 240Hz 10-bit RGB. The monitor specification should state the supported rate and its conditions.
UHBR20
UHBR20 is the 80.0 Gbps class and has the 77.37 Gbps maximum payload cited by VESA. It is the DisplayPort choice when you want the greatest uncompressed headroom and both endpoints implement it. A UHBR20-capable GPU connected to a UHBR10 monitor is limited by the monitor; a UHBR20 monitor connected to a lower-tier GPU is limited by the GPU.
VESA describes DisplayPort 2.1 as converging with USB4 physical-layer specifications to support high video performance across consumer products. That standards convergence does not change the need to verify the exact implementation in a particular graphics card, dock, USB-C port or monitor.
HDMI 2.1: lower ceiling, broad practical compatibility
HDMI 2.1 has a 48.0 Gbps link and approximately 42.6 Gbps payload in the comparison cited above. It can carry many 4K high-refresh modes, especially when the display uses DSC, a reduced timing, 8-bit output or chroma subsampling. It has less spare capacity than UHBR20 for simultaneously demanding 4K, 240Hz, 10-bit, RGB and HDR.
HDMI 2.1 is often the practical winner when the display is designed like a television, when a console is the source, or when the graphics card offers HDMI 2.1 as its strongest common port. It also avoids adapters in setups where the monitor has HDMI but no high-rate DisplayPort input. Do not assume every HDMI-labeled input is 48 Gbps: RTINGS has documented HDMI 2.1 monitors with 24 Gbps implementations. Read the input specification and the monitor’s mode table.
Rank #3
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How DSC changes the comparison
Display Stream Compression is not a workaround limited to one connector. NVIDIA states that DSC is used with DisplayPort 1.4 and newer as well as HDMI 2.1. VESA reported in its 2022 DisplayPort 2.1 release that DSC can reduce transport bandwidth by more than 67 percent.
That reduction is why a 4K 240Hz monitor can offer 10-bit RGB and HDR on a link whose uncompressed payload would be insufficient. The exact compression ratio and image format are negotiated by the GPU and display; the published “up to more than 67 percent” figure is not a promise that every mode uses that exact reduction.
What to confirm about DSC
- Whether DSC is supported on the specific input, not merely somewhere in the monitor’s product family.
- Whether the desired refresh rate, HDR mode and bit depth require DSC.
- Whether enabling DSC disables another feature, such as a second input mode, a high-bit-depth option or a built-in KVM function.
- Whether the GPU driver exposes the desired combination as RGB, 4:4:4, 10-bit and HDR rather than silently selecting a lower-quality format.
- Whether a dock, adapter or USB-C Alt Mode path passes DSC; an intermediate device can limit the mode even when the GPU and monitor support it.
On most systems DSC is automatic. Treat it as a system capability to verify, not as a cable feature that can be added by buying a faster-looking lead.
Color depth, HDR and variable refresh
Color depth has a direct bandwidth cost. Moving from 8-bit to 10-bit increases the pixel data by 25 percent before transport overhead, so a mode that works at 8-bit may require DSC at 10-bit. HDR typically makes 10-bit output desirable, but the monitor’s specification may limit HDR at its maximum refresh rate or on a particular input.
Keep the output in RGB or YCbCr 4:4:4 for ordinary PC use when possible. If the driver offers only YCbCr 4:2:2 or 4:2:0 at the target refresh, that is evidence the available link or timing cannot carry the requested full-chroma format without another change.
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Both interfaces can carry variable-refresh technology, but the implementation is not universal. DisplayPort commonly uses VESA Adaptive-Sync, with FreeSync or G-SYNC compatibility determined by the GPU, monitor and driver. HDMI 2.1 includes an HDMI variable-refresh mechanism, while a monitor may additionally advertise console-oriented features. Check the exact compatibility list and operating range; connector type alone does not guarantee VRR.
Cable choice: certification is part of the link
For DisplayPort UHBR20
Use a VESA-certified DP80 cable when both endpoints support UHBR20. DP80 is the certification class intended for the highest UHBR rates. Choose a cable appropriate to the required length and avoid unverified passive cables when operating near the maximum rate. A cable that works at a lower refresh rate can still fail when the link trains at UHBR20.
For HDMI 2.1
Use an Ultra High Speed HDMI cable rated for the required 48 Gbps class. The label matters because a cable sold alongside an older HDMI product may not meet the signaling requirement, even though the connector fits. If the monitor falls back to a lower refresh rate, loses HDR, or repeatedly blanks, test with a known-certified cable of the shortest practical length.
What certification cannot fix
- A monitor input limited to 24 Gbps cannot become a 48 Gbps input through a cable.
- A DisplayPort 2.1 UHBR10 source cannot be upgraded to UHBR20 by changing the cable.
- An adapter, dock or switch may impose its own bandwidth ceiling.
- Longer cable runs have less signal margin; certification for a class does not mean every length behaves identically in every installation.
Comparison for common high-refresh targets
| Requirement | DisplayPort 2.1 UHBR20 | DisplayPort 2.1 UHBR10/13.5 | HDMI 2.1 |
|---|---|---|---|
| Maximum stated payload | 77.37 Gbps | Not stated as one common figure; depends on tier | Approximately 42.6 Gbps |
| 4K 240Hz 8-bit RGB | Most headroom; may be uncompressed depending on timing | Monitor-specific; DSC may be required | Monitor-specific; DSC or a reduced timing may be required |
| 4K 240Hz 10-bit RGB/HDR | Best chance of avoiding compression, but verify the mode table | Often a DSC use case | Commonly a DSC use case |
| VRR | Supported when GPU and monitor implement compatible Adaptive-Sync or G-SYNC features | Same compatibility requirement | Supported when the display and source implement compatible HDMI VRR features |
| Best cable class | VESA-certified DP80/UHBR20 | Cable rated for the actual UHBR tier | Ultra High Speed HDMI, 48 Gbps class |
| Typical source advantage | High-end desktop GPUs with UHBR20 outputs | GPUs and laptops whose port is labeled DP 2.1 but specifies a lower tier | Consoles, TVs and displays whose strongest common input is HDMI 2.1 |
“Typical source advantage” describes connection patterns, not a guarantee for a particular model. The port list and supported timings in the product manuals take precedence.
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How to check a monitor and GPU before buying
- Write down the exact target mode. Include resolution, refresh rate, RGB or chroma format, bit depth, HDR and VRR. “4K 240Hz” alone is not a complete requirement.
- Inspect the monitor input table. Look for the input’s stated bandwidth, the DP UHBR tier or HDMI implementation, maximum refresh rate, DSC notes and any limits attached to HDR or 10-bit output.
- Inspect the GPU output specifications. Confirm which physical connector provides the required rate. A card can have DisplayPort 2.1 and HDMI 2.1 simultaneously while implementing different capabilities on each.
- Check the path between them. Include USB-C Alt Mode, docks, adapters, KVM switches and capture devices. The weakest component controls link training.
- Match the cable certification. Use DP80 for a UHBR20 connection or an Ultra High Speed HDMI cable for a 48 Gbps HDMI link.
- Read the monitor manual for feature interactions. Some displays reserve a maximum refresh rate for one input or require a menu setting to enable the full-speed mode.
Setting up 4K 240Hz after installation
- Connect the monitor directly to the GPU rather than through a dock or unverified switch.
- Open the monitor’s on-screen display and select its highest-bandwidth DisplayPort or HDMI mode if such a setting exists.
- Install the current GPU driver and select the monitor’s native 3840×2160 resolution and 240Hz refresh rate in the operating system or driver control panel.
- Set the output color format to RGB or 4:4:4, select 10-bit when HDR and the monitor support it, and enable HDR only after the high-refresh mode is stable.
- Enable Adaptive-Sync, G-SYNC-compatible mode or HDMI VRR according to the monitor and GPU instructions, then verify that the reported refresh range is active.
- Confirm the negotiated result with the GPU control panel or monitor information screen. Check the reported refresh rate, bit depth, color format and HDR status rather than relying on the cable label.
Troubleshooting a missing 240Hz option
The display tops out at 120Hz or 144Hz
- Verify that the cable is connected to the GPU output and the monitor input specified for the highest rate.
- Check whether the monitor menu is set to a compatibility or reduced-bandwidth mode.
- Remove adapters, docks and switches and test a direct connection.
- Confirm the monitor’s 240Hz mode is available at the selected resolution and color depth; some specifications list 240Hz only for 8-bit or DSC-enabled output.
240Hz works but HDR or 10-bit disappears
The combined data requirement may exceed the selected link’s payload. Check whether DSC is enabled and supported on that input. If DSC is unavailable, the choices may be a lower refresh rate, 8-bit output, a different timing or chroma subsampling. Use RGB/4:4:4 for text-critical work unless the display’s documented limitations leave no alternative.
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The screen blanks, flickers or shows link errors
- Replace the cable with a certified DP80 or Ultra High Speed HDMI cable of a practical length.
- Lower the refresh rate temporarily. If the fault disappears, the link is operating near its margin.
- Test without a switch, KVM, dock or adapter.
- Update the GPU driver and monitor firmware where the manufacturer provides an update.
- Try the other high-bandwidth input to determine whether the issue is limited to one connector or mode.
Text looks blurry despite a high refresh rate
Open the driver information panel and check for YCbCr 4:2:2 or 4:2:0. Chroma subsampling can make colored text and fine UI edges look soft. Select RGB or 4:4:4, enable DSC if available, or reduce refresh rate until full-chroma output is possible.
Multi-monitor considerations
Running several monitors changes the decision because every output consumes GPU display bandwidth and may use a separate transport path. A high-refresh 4K panel can coexist with lower-resolution side displays, but the GPU, dock or MST hub must support the requested combination. DisplayPort’s daisy-chain and MST features can simplify cabling, yet the shared link and hub still have a finite capacity. For a 4K 240Hz primary monitor, connect it directly to the highest-rate GPU output first, then add secondary displays and verify that the primary mode remains available.
HDMI is generally point-to-point, so it avoids MST bandwidth sharing but may leave fewer suitable outputs on a desktop GPU. On a laptop, USB-C DisplayPort Alt Mode can be convenient, but its available lanes may be shared with USB data and can reduce video capability. Check the computer’s port specification rather than treating every USB-C connector as equivalent.
Which interface should you choose?
Choose DisplayPort 2.1 UHBR20 when
- Both the GPU and monitor explicitly list UHBR20.
- You want the greatest chance of running 4K 240Hz, 10-bit RGB and HDR with minimal reliance on compression.
- You can use a VESA-certified DP80 cable and a direct connection.
- Your setup is a desktop PC where DisplayPort is the strongest output on the graphics card.
Choose HDMI 2.1 when
- HDMI 2.1 is the strongest common port on the source and display.
- You are connecting a console or television-style display.
- The monitor’s HDMI input is documented as a full 48 Gbps implementation and supports the exact target mode.
- Your DisplayPort input is only UHBR10, unavailable, or limited by an adapter or dock.
Choose based on the mode table, not the logo, when
- The monitor says only “DisplayPort 2.1” without UHBR10, UHBR13.5 or UHBR20.
- The product lists “HDMI 2.1” but does not state whether the input is 24 or 48 Gbps.
- You require 4K 240Hz with 10-bit HDR, because DSC and color-depth limits may determine the result.
- You are using USB-C, a dock, an adapter, a KVM or a long cable run.
The practical rule is simple: use UHBR20 plus a certified DP80 cable for maximum headroom when both endpoints support it; otherwise use the highest-rated HDMI 2.1 or DisplayPort path that explicitly supports your desired resolution, refresh rate, color depth, HDR and VRR combination. No universal refresh-rate maximum exists independently of the specific monitor and GPU.
Quick Recap
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