The number of displays you can use with Elgato Thunderbolt™ 2 Dock depends on the power of your computer’s graphics system, the type of displays you’re trying to use, and whether you're using a Mac or PC.
The following is an exhaustive listing of how you can use up to two monitors with Elgato Thunderbolt™ 2 Dock in various configurations.
To check to see if your Mac can support two monitors via Thunderbolt™, see Apple Technote http://support.apple.com/kb/ht5219#18
See the end of this article for a more technical explanation of why such limitations exist.
The Only Monitor is a DisplayPort Monitor
Mac:
You can use one DisplayPort monitor with the Elgato Thunderbolt™ 2 Dock, by connecting it to the Thunderbolt™ port.
This will work as long as no other monitor is connected to the HDMI port - if an HDMI monitor is connected, it will take precedence over the DisplayPort monitor, and the DisplayPort monitor will not work.
PC:
You can use one DisplayPort monitor with Elgato Thunderbolt™ 2 Dock, by connecting it to the Thunderbolt™ port.
This will work as long as no other monitor is connected to the HDMI port - if an HDMI monitor is connected, it will take precedence over the DisplayPort monitor, and the DisplayPort monitor will not work.
The Only Monitor is a HDMI Monitor
Mac:
You can use one HDMI monitor with Elgato Thunderbolt™ 2 Dock.
PC:
You can use one HDMI monitor with Elgato Thunderbolt™ 2 Dock.
The Only Monitor is a Apple Thunderbolt Display
Mac:
You can use one Apple Thunderbolt Display with Elgato Thunderbolt™ 2 Dock.
PC:
You can use one Apple Thunderbolt Display with Elgato Thunderbolt™ 2 Dock.
One HDMI Monitor and One Apple Thunderbolt Display
Mac:
When using a powerful enough Mac, you can connect an HDMI display and an Apple Thunderbolt Display to Elgato Thunderbolt™ 2 Dock at the same time.
PC:
When using a powerful enough PC that has two Thunderbolt™ ports, you can connect an HDMI display and an Apple Thunderbolt Display to Elgato Thunderbolt™ 2 Dock at the same time.
Please Note:
On PC motherboards, only the boards with two Thunderbolt™ ports provide each port with two display signals. In that setup, you would run one Thunderbolt™ cable from your PC to Elgato Thunderbolt™ 2 Dock, but it would be carrying two display signals.
One HDMI Monitor and One DisplayPort Monitor - WILL NOT WORK
Mac:
When using a Mac, you can’t connect an HDMI monitor and DisplayPort monitor to Elgato Thunderbolt™ 2 Dock at the same time. Only one monitor will work.
PC:
When using a PC, you can’t connect an HDMI display and DisplayPort display to Elgato Thunderbolt™ 2 Dock at the same time. Only one monitor will work.
Please Note:
Any video adapter that uses Thunderbolt™ or DisplayPort counts as a DisplayPort monitor for the sake of this article.
Any adapter that uses HDMI counts as a HDMI monitor the sake of this article.
That means you can't use a HDMI monitor (or adapter attached to the HDMI port) and a DisplayPort (or Thunderbolt™) adapter at the same time. Only one monitor connection would work.
For example:
• A DisplayPort (or Thunderbolt™) to DVI adapter can't be used at the same time as a HDMI monitor
• A DisplayPort (or Thunderbolt™) to VGA adapter can't be used at the same time as a HDMI monitor
• A DisplayPort (or Thunderbolt™) to HDMI adapter can't be used at the same time as a HDMI monitor
Other combinations using various standards also won't work.
Simply put, you can't use a DisplayPort and HDMI connection at the same time - only one will work.
Two Displays Via Two Thunderbolt™ Docks
Mac:
You can connect an HDMI display, and then connect the Elgato Thunderbolt™ 2 Dock to another Elgato Thunderbolt™ 2 Dock via a Thunderbolt™ cable.
Then, the second Elgato Thunderbolt™ 2 Dock can connect to a display via Thunderbolt™, HDMI or DisplayPort.
PC:
When using a powerful enough PC that has two Thunderbolt™ ports, you can connect an HDMI display, and then connect Elgato Thunderbolt™ 2 Dock to another Elgato Thunderbolt™ 2 Dock via a Thunderbolt™ cable.
Then, the second Elgato Thunderbolt™ 2 Dock can connect to a display via Thunderbolt™, HDMI or DisplayPort.
Please Note:
On PC motherboards, only the boards with two Thunderbolt™ ports provide each port with two display signals. In that setup, you would run one Thunderbolt™ cable from your PC to Elgato Thunderbolt™ 2 Dock, but it would be carrying two display signals.
This setup won't work on Macs in Bootcamp.
One Thunderbolt™ Dock Can Only Run Two Displays At A Time
Mac:
The Thunderbolt™ signal from a Mac has up to two display signals in it. Therefore, no more than two monitors can be connected to Elgato Thunderbolt™ 2 Dock at the same time.
PC:
The Thunderbolt™ signal from a PC usually only has one display signal in it.
The exception is a PC that has two Thunderbolt™ ports. Only PC motherboards with two Thunderbolt™ ports provide each port with two display signals. In that setup, you would run one Thunderbolt™ cable from your PC to Elgato Thunderbolt™ 2 Dock, but it would be carrying two display signals.
No more than two monitors can be connected to Elgato Thunderbolt™ 2 Dock at the same time.
Exceptional Cases
1) DisplayPort monitors will not function if connected to the Thunderbolt™ port of an Apple Thunderbolt Display.
See Apple Technote http://support.apple.com/kb/ht5219#20
2) Any monitors cascaded after an Apple Thunderbolt Display won't work.
Why Are There Restrictions On How Many Displays Can Be Used?
Thunderbolt™ has PCIe and DisplayPort signals multiplexed together.
There can be up to two DisplayPort signals available on the Thunderbolt™ bus, depending on the Mac or PC.
When the DisplayPort signals come from the computer over Thunderbolt™, and travel into the Elgato Thunderbolt™ 2 Dock, one of them is demultiplexed. That DisplayPort signal is ready to be used.
The demultiplexed DisplayPort signal is translated by the Elgato Thunderbolt™ 2 Dock into HDMI. That leaves one DisplayPort signal still multiplexed in the Thunderbolt™ signal, for later use in the Thunderbolt™ chain.
That second DisplayPort signal can only be demultiplexed by another Thunderbolt™ device, like the Apple Thunderbolt Display, or by another Elgato Thunderbolt™ 2 Dock.
If you connect a DisplayPort monitor to the Thunderbolt™ connection when the HDMI port is in use, the DisplayPort monitor will not light up. In this case, only Thunderbolt™ signaling is available at the Thunderbolt™ connection, which the DisplayPort monitor does not understand.
When you try to connect two non-Thunderbolt™ monitors to the Elgato Thunderbolt™ 2 Dock, you can either get a signal over the HDMI port, or via DisplayPort, but not both at the same time.
If you choose to use a HDMI device, then one multiplexed signal remains, associated with the Thunderbolt™ port, available for Thunderbolt™ devices only.
If you choose DisplayPort (via the Thunderbolt™ port), then the Thunderbolt™ bus is terminated, when it comes to display signals. The DisplayPort monitor will work, but the HDMI port will not.
The following is an exhaustive listing of how you can use up to two monitors with Elgato Thunderbolt™ 2 Dock in various configurations.
To check to see if your Mac can support two monitors via Thunderbolt™, see Apple Technote http://support.apple.com/kb/ht5219#18
See the end of this article for a more technical explanation of why such limitations exist.
The Only Monitor is a DisplayPort Monitor
Mac:
You can use one DisplayPort monitor with the Elgato Thunderbolt™ 2 Dock, by connecting it to the Thunderbolt™ port.
This will work as long as no other monitor is connected to the HDMI port - if an HDMI monitor is connected, it will take precedence over the DisplayPort monitor, and the DisplayPort monitor will not work.
PC:
You can use one DisplayPort monitor with Elgato Thunderbolt™ 2 Dock, by connecting it to the Thunderbolt™ port.
This will work as long as no other monitor is connected to the HDMI port - if an HDMI monitor is connected, it will take precedence over the DisplayPort monitor, and the DisplayPort monitor will not work.
The Only Monitor is a HDMI Monitor
Mac:
You can use one HDMI monitor with Elgato Thunderbolt™ 2 Dock.
PC:
You can use one HDMI monitor with Elgato Thunderbolt™ 2 Dock.
The Only Monitor is a Apple Thunderbolt Display
Mac:
You can use one Apple Thunderbolt Display with Elgato Thunderbolt™ 2 Dock.
PC:
You can use one Apple Thunderbolt Display with Elgato Thunderbolt™ 2 Dock.
One HDMI Monitor and One Apple Thunderbolt Display
Mac:
When using a powerful enough Mac, you can connect an HDMI display and an Apple Thunderbolt Display to Elgato Thunderbolt™ 2 Dock at the same time.
PC:
When using a powerful enough PC that has two Thunderbolt™ ports, you can connect an HDMI display and an Apple Thunderbolt Display to Elgato Thunderbolt™ 2 Dock at the same time.
Please Note:
On PC motherboards, only the boards with two Thunderbolt™ ports provide each port with two display signals. In that setup, you would run one Thunderbolt™ cable from your PC to Elgato Thunderbolt™ 2 Dock, but it would be carrying two display signals.
One HDMI Monitor and One DisplayPort Monitor - WILL NOT WORK
Mac:
When using a Mac, you can’t connect an HDMI monitor and DisplayPort monitor to Elgato Thunderbolt™ 2 Dock at the same time. Only one monitor will work.
PC:
When using a PC, you can’t connect an HDMI display and DisplayPort display to Elgato Thunderbolt™ 2 Dock at the same time. Only one monitor will work.
Please Note:
Any video adapter that uses Thunderbolt™ or DisplayPort counts as a DisplayPort monitor for the sake of this article.
Any adapter that uses HDMI counts as a HDMI monitor the sake of this article.
That means you can't use a HDMI monitor (or adapter attached to the HDMI port) and a DisplayPort (or Thunderbolt™) adapter at the same time. Only one monitor connection would work.
For example:
• A DisplayPort (or Thunderbolt™) to DVI adapter can't be used at the same time as a HDMI monitor
• A DisplayPort (or Thunderbolt™) to VGA adapter can't be used at the same time as a HDMI monitor
• A DisplayPort (or Thunderbolt™) to HDMI adapter can't be used at the same time as a HDMI monitor
Other combinations using various standards also won't work.
Simply put, you can't use a DisplayPort and HDMI connection at the same time - only one will work.
Two Displays Via Two Thunderbolt™ Docks
Mac:
You can connect an HDMI display, and then connect the Elgato Thunderbolt™ 2 Dock to another Elgato Thunderbolt™ 2 Dock via a Thunderbolt™ cable.
Then, the second Elgato Thunderbolt™ 2 Dock can connect to a display via Thunderbolt™, HDMI or DisplayPort.
PC:
When using a powerful enough PC that has two Thunderbolt™ ports, you can connect an HDMI display, and then connect Elgato Thunderbolt™ 2 Dock to another Elgato Thunderbolt™ 2 Dock via a Thunderbolt™ cable.
Then, the second Elgato Thunderbolt™ 2 Dock can connect to a display via Thunderbolt™, HDMI or DisplayPort.
Please Note:
On PC motherboards, only the boards with two Thunderbolt™ ports provide each port with two display signals. In that setup, you would run one Thunderbolt™ cable from your PC to Elgato Thunderbolt™ 2 Dock, but it would be carrying two display signals.
This setup won't work on Macs in Bootcamp.
One Thunderbolt™ Dock Can Only Run Two Displays At A Time
Mac:
The Thunderbolt™ signal from a Mac has up to two display signals in it. Therefore, no more than two monitors can be connected to Elgato Thunderbolt™ 2 Dock at the same time.
PC:
The Thunderbolt™ signal from a PC usually only has one display signal in it.
The exception is a PC that has two Thunderbolt™ ports. Only PC motherboards with two Thunderbolt™ ports provide each port with two display signals. In that setup, you would run one Thunderbolt™ cable from your PC to Elgato Thunderbolt™ 2 Dock, but it would be carrying two display signals.
No more than two monitors can be connected to Elgato Thunderbolt™ 2 Dock at the same time.
Exceptional Cases
1) DisplayPort monitors will not function if connected to the Thunderbolt™ port of an Apple Thunderbolt Display.
See Apple Technote http://support.apple.com/kb/ht5219#20
2) Any monitors cascaded after an Apple Thunderbolt Display won't work.
Why Are There Restrictions On How Many Displays Can Be Used?
Thunderbolt™ has PCIe and DisplayPort signals multiplexed together.
There can be up to two DisplayPort signals available on the Thunderbolt™ bus, depending on the Mac or PC.
When the DisplayPort signals come from the computer over Thunderbolt™, and travel into the Elgato Thunderbolt™ 2 Dock, one of them is demultiplexed. That DisplayPort signal is ready to be used.
The demultiplexed DisplayPort signal is translated by the Elgato Thunderbolt™ 2 Dock into HDMI. That leaves one DisplayPort signal still multiplexed in the Thunderbolt™ signal, for later use in the Thunderbolt™ chain.
That second DisplayPort signal can only be demultiplexed by another Thunderbolt™ device, like the Apple Thunderbolt Display, or by another Elgato Thunderbolt™ 2 Dock.
If you connect a DisplayPort monitor to the Thunderbolt™ connection when the HDMI port is in use, the DisplayPort monitor will not light up. In this case, only Thunderbolt™ signaling is available at the Thunderbolt™ connection, which the DisplayPort monitor does not understand.
When you try to connect two non-Thunderbolt™ monitors to the Elgato Thunderbolt™ 2 Dock, you can either get a signal over the HDMI port, or via DisplayPort, but not both at the same time.
If you choose to use a HDMI device, then one multiplexed signal remains, associated with the Thunderbolt™ port, available for Thunderbolt™ devices only.
If you choose DisplayPort (via the Thunderbolt™ port), then the Thunderbolt™ bus is terminated, when it comes to display signals. The DisplayPort monitor will work, but the HDMI port will not.