What does "AIC" mean? What does the connector do? Is it like a USB pin header where you can connect for example your USB ports for your case? Or do you need something else?

Also there are expansion cards, but I don't know if you need the AIC connector together with a PCIe 4x slot.

Can also someone explain for what reason you want to connect the displayport input with a graphics card (all on the same machine)?

3 Answers 3


Mainly, Thunderbolt consists of 4 PCI Express lanes (the PCIe version depends on the Thunderbolt version) and a DisplayPort connection. An Add-in card (AIC) gets these from the PCIe slot and the DisplayPort cable you plug into the card.

However, it is not enough to simply connect the cable to the PCI Express interfaces already present on your mainboard. Therefore, the card makes an additional connection, using the so-called GPIO (General-purpose I/O) header. Unfortunately, the exact nature of this connection is not documented. It is probably used by the chipset to dynamically reassign PCIe lanes as required.

The additional connector is required, the AIC will not work without it.

  • According to PC Perspective, "These TB_Headers, on ASUS motherboards, are General Purpose I/O (GPIO) connections used for a fairly unclear task. Officially, they help facilitate a DisplayPort connection to the integrated GPU although they are required even if using DisplayPort pass-through." So that's another idea for its purpose. Jan 11, 2016 at 21:27
  • To rephrase it: If a motherboard has a Thunderbolt AIC connector you can't do anything with it. First you need an add-in card. Then you have to connect it to a Displayport connector (output) of your mother board. Therefore the AIC needs a Displayport input. Finally, you also have to connect the AIC with the AIC connector/GPIO of your motherboard. Do I get it right? Do you also need the additional displayport chain for Displayport 3?
    – testing
    Jan 11, 2016 at 21:35
  • @testing Yes, that sounds about right. Although you could also use a dedicated graphics card’s DP output. I don’t know what you mean by “additional DisplayPort chain”, though.
    – Daniel B
    Jan 13, 2016 at 18:57
  • With "additional DisplayPort chain” I mean the extra cable connection from the Displayport connector of your motherboard to the AIC. So is it the same behavior here or did something change with Displayport 3?
    – testing
    Jan 13, 2016 at 19:00
  • 2
    There’s no such thing as DisplayPort 3. There’s Thunderbolt 3, though. It’s still the same, of course. The PCIe interface does not offer a DisplayPort connection, so it has to come from elsewhere. There are no internal connectors for it either, so it’ll remain external. It could even be external with onboard Thunderbolt, to allow for connections to dedicated graphics cards.
    – Daniel B
    Jan 13, 2016 at 19:03

AIC = Add-In Card

You can transmit DisplayPort signals through Thunderbolt; more tidbits of information are at Can I connect a DisplayPort monitor to the Thunderbolt port on a Mac, and vice-versa?. For later versions of TB, you can daisy-chain displays, which could result in less clutter.

Asus call the AIC connector lead a "system-link cable", which leaves me none-the-wiser as to its purpose.

I do not know if you could operate a TB AIC without the DP input - I do not have the necessary parts to test that, and it could depend on if the driver insisted on having a DP input.


Here is an example of an Add-in-card:


In the downloads tab/section there is a pdf that explains how it is plugged in to the 'Thunderbolt Header' on the motherboard, in addition to the PCIe x4 slot, as you suggested in your question.

The AIC has displayport sockets (input), and thunderbolt connectors (output). So I suppose it allows you to re-route an external (or internal) graphics card output to the displayport connectors, in addition to anything via the PCIe bus.

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