Active vs Passive DisplayPort Adapters – What You Need to Know
If you need to send a DisplayPort or Mini DisplayPort signal from your video source device to a DVI, VGA, or HDMI monitor, you’ll need an adapter. But how do you know which one to choose? There’s often a lot of confusion around DisplayPort adapters, specifically the difference between an Active and Passive adapter. We thought it would be helpful to highlight the differences below. Especially the fact that only two passive DP adapters should be used per card. Beyond this active adapters must be used due to the GPU typically only having two clock signals available for the passive adapters, which don’t generate their own clock signal/timing to utilize.
Active DisplayPort Adapters
• Uses video converter chips inside the adapter for signal conversion
• More expensive due to additional chips
• Necessary when source does not support dual-mode DisplayPort (DP++)
• Converts both single-mode and dual-mode DisplayPort
• Analog VGA and dual-link DVI require powered active adapters to convert protocol and signal levels. (VGA adapters are powered by the DisplayPort Connector while dual-link DVI adapters may rely on an external power source)
• May be necessary if graphics card cannot support DP++ output on the maximum number of monitors
Passive DisplayPort Adapters
• Cheaper than active adapters
• Only a maximum of two passive adapters can be used per GPU, due to the fact that each GPU only has 2 clock sync signals for the passive adapter to utilize
• Relies on DisplayPort or Mini DisplayPort sources that support dual-mode (DP++)
• DP++ source can use a passive adapter to convert DisplayPort signals to single-link DVI or HDMI
• DP++ video source performs the conversion instead of the adapter
Connecting to Multiple Monitors
When connecting your DisplayPort video source to multiple VGA, DVI, or HDMI monitors, you will most likely need an active adapter or splitter. Regardless of whether your video source supports DP++, an active adapter or splitter will be required. This is due to some graphic cards not being able to support DP++ output on the max number of monitors. Since most device capabilities vary, you will need to check with the graphics card manufacturer for the type of adapter that’s best suited for your project.
DisplayPort Multi-Stream Transport (MST) hubs are also a viable option for better functionality when connecting multiple monitors to a DisplayPort video source. However, be sure your graphic card can support DisplayPort 1.2 standards in order to take full advantage of MST features.
Other Helpful Information
• Some GPUs/DisplayPort equipment have very specific requirements around which Active DP cables may be used (Specific manufacturers, models) due to timing and other design considerations