However, that does offer another route for you to investigate.

I have to presume that they can only work on cards that the software maker has all the secret non-standard suff for and that you must customize the software a bit when you install it. There are some third-party fan control software tools that include the ability to control the video card fan system. So obviously they have a way to make their card's temp sensor info available through the PCIe bus, but there's still so standard way that a mobo maker could rely on. Many video cards come with management software that somehow can display the cards' temperature, and ALSO allows YOU to set up your own version of how the card's cooling fan responds to temperature changes. Other video card makers have a small part of this done, but not so you could use it. So, on some of their mobos IF you also install one of that same maker's video cards, this trick can be done. There is at least one mobo maker who also makes video cards, and they have created their own 'brand-specific' non-standard way to do this. So no mobo maker can be sure that any video card plugged into its slots will give it such info to use for fan control. The root of this problem is that there never has been any industry-standard way for an added video card (in a PCIe slot, typically) to send out to the mobo the video card temperature sensor signal.

Msi motherboard fan control software