Cable Troubleshooting
Most HDMI, DVI, and DisplayPort problems come down to a handful of causes: a cable without enough bandwidth for the resolution, an HDCP handshake failure, an EDID handshake hiccup after sleep, DVI carrying no audio, or a passive adapter used in the wrong direction. Find your symptom below for the fix.
Before anything else, try the universal first steps: confirm the display is on the correct input, reseat the cable at both ends, swap in a known-good cable, try another port, and power-cycle both devices by unplugging them for 30 seconds.
Why is my display showing "No Signal"?
Work through the basics in order:
- Make sure the display is set to the correct input.
- Reseat the cable firmly at both ends, and try a different cable and a different port.
- Power-cycle both devices — unplug them for 30 seconds.
- If an adapter is involved, confirm it is the right type and direction (passive vs active) and that the cable supports your resolution.
Why does my screen go black after waking from sleep?
This is usually an EDID or HDCP handshake problem when devices renegotiate after sleep. Reseat the cable, update your graphics drivers, turn off aggressive power saving (HDMI link power management or display "deep sleep"), and try a different port. Some TVs and monitors need a firmware update to fix wake-from-sleep handshakes.
Why won't my 4K or HDR picture work at 60 Hz or 120 Hz?
Three common causes:
- Cable bandwidth too low — use Premium High Speed for 4K at 60 Hz with HDR, and Ultra High Speed for 4K at 120 Hz or 8K.
- Port mode not enabled — many TVs need an "HDMI Ultra HD Deep Color" / "Enhanced" / "HDMI 2.1" setting turned on per input.
- A device in the chain does not support the mode or HDCP 2.2/2.3.
Why is there no sound over my DVI-to-HDMI connection?
DVI carries video only, so a DVI-to-HDMI cable or adapter passes the picture but not audio. Connect a separate audio cable between the devices, or switch the source to a native HDMI or DisplayPort output that carries audio. See DVI vs HDMI for details.
Why does my picture flicker, sparkle, or cut out?
Intermittent sparkles ("sparklies") or dropouts usually mean the signal is degrading — often on a long or low-quality cable running near its bandwidth limit. Use a shorter or certified cable, switch to an Active or Active Optical (AOC) cable for long runs, and reseat both connectors. Interference or a failing port can also be the cause.
Why does my passive DisplayPort-to-HDMI or USB-C-to-HDMI adapter show nothing?
Passive adapters only work from a DisplayPort or USB-C source to an HDMI display, and only if the source supports Dual-Mode DisplayPort (DP++) or DisplayPort Alt Mode. Going from an HDMI source to a DisplayPort display — or from a port without DP++ support — requires an active adapter with a conversion chip. See HDMI vs DisplayPort.
Why does protected or 4K content show a black screen or HDCP error?
This is an HDCP copy-protection mismatch. Every device in the chain — display, AV receiver, splitter, and any adapter — must support HDCP 2.2 or 2.3 to pass protected 4K content. A single non-compliant link blanks the screen or drops the resolution. Connect the source directly to the TV to isolate the offending device. See what HDCP is.
Still stuck? Use the Cable Selector Guide to confirm you have the right cable or adapter, check the Connector Compatibility Matrix, or review HDMI cable types to be sure your cable has enough bandwidth.
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