What is dual-link DVI?
Dual-link is a DVI configuration with two TMDS links instead of one. Single-link DVI has three data channels and a clock; dual-link adds three more data channels that share the same clock, roughly doubling the bandwidth. That extra capacity supports 2560x1600 at 60 Hz, and 1920x1080 at 120 or 144 Hz, which single-link DVI can't carry.
Dual-link is available on DVI-D (digital only) and DVI-I (digital plus analog). DVI-A is analog only and has no dual-link version.
Spotting a dual-link connector
Look at the middle of the pin grid. A dual-link connector has the full 24 pins in three rows of eight; a single-link connector leaves out the six center pins. DVI-D dual-link is 24 + 1 pins (the blade), and DVI-I dual-link is 24 + 5 (the blade plus four analog pins around it).
What you need for dual-link to work
- A dual-link output on the graphics card.
- A dual-link cable. A single-link cable fits the same sockets but carries only one link.
- A dual-link input on the monitor.
If any piece is single-link, the display falls back to single-link bandwidth. Symptoms include a resolution below the monitor's native one, 60 Hz on a 144 Hz monitor, or no picture at full resolution. Adapters matter too: passive adapters to HDMI carry only one link, and a DisplayPort to dual-link DVI adapter must be an active adapter, often powered over USB.
No audio
The second link adds video bandwidth, not sound. DVI, single-link or dual-link, carries no audio in its standard, so a DVI-connected display needs a separate audio connection, or switch to HDMI or DisplayPort to get video and audio on one cable.
For the CompTIA A+ exam
Core 1 (220-1201) objective 3.2 lists DVI among video cables. Dual-link isn't named, but the facts that matter are simple: dual-link means more resolution and refresh rate, its connector has the full pin grid, and DVI never carries audio. Objective 5.3 lists audio issues among display symptoms, and with DVI the cause is the interface, not a bad cable.