Hi All,

does the USB Type C for expansion cards support HDMI ALT mode or only DP ALT mode?


DP alt mode only. Much better only supporting one display alt mode rather than two as it requires more circuitry.

Hi Josh,

where did you find this info, is there a manual for the USB Type C for expansion connector form the framework side?

Aside of that is the DP alt mode DP++ capable or only DP ?

It is capable of 4k 60hz with 3 monitors external and 1 internal. No manual apart from their github. Your all on your own after that. Apart from the community :wink: As long as you comply with the spec of Type C you should be ok.

The source of the DisplayPort signal is the Tiger Lake CPU. I suppose there’s probably Intel documentation for the CPU that might describe its integrated GPU and its integrated Thunderbolt4/USB4 functionality.

With Thunderbolt 4/USB 4 functionality, you also get DisplayPort Alt Mode because it’s exposed as a Thunderbolt 4/USB 4 USB-C port. I don’t think Intel makes anything that includes HDMI Alt Mode, so adding that would require some extra chips and take more space on the motherboard.

From a USB-C port, DP++ (DisplayPort Dual Mode) is not a thing otherwise it would be HDMI Alt Mode. I’ve never seen an example of HDMI Alt Mode. Do you know of an example? Probably, any HDMI output from a USB-C port is using a DisplayPort Alt Mode to a DisplayPort to HDMI adapter (including the Framework Laptop’s HDMI expansion card).

If you look at something like the HP Thunderbolt Dock G2, it has a Titan Ridge Thunderbolt controller which has a DisplayPort output that is connected internally to a DisplayPort 1.4 MST Hub with three DisplayPort outputs. Two of those outputs are exposed as DP++ capable DisplayPort ports. The third port is exposed as a USB-C port that supports DisplayPort Alt Mode. The third port is also used for the docks’s VGA output which disables DisplayPort Alt Mode of the USB-C port when connected. That’s ok since the USB-C port can still be used for USB data. You should be able to connect three 4K60 displays to these three ports (the MST Hub converts HBR3 x4 + DSC MST to three HBR2 x4 SST outputs). The dock’s downstream Thunderbolt port has a separate DisplayPort connection if you choose to use that port (because Thunderbolt can carry two DisplayPort signals) but the Framework Laptop is limited to 4 displays including the built-in display.

If you close the laptop and are ONLY using external displays, can you attach 4? I’m thinking 1 USB-C monitor supplying power plus 3x DP/HDMI cards?

Or maybe silly because you could only run for a few hours on battery, what about closing the laptop and running 4x DP/HDMI displays (using a BT keyboard and mouse since all the ports would be otherwise occupied)?

Yep, 4 external displays with the laptops display off.