Just a head's up, that will not work. While the onboard ports do operate as USB2, they still use the same USB3 host controller as the other ports. Meaning, they won't work without proper drivers for the USB3 controller.
There is a plethora of info on how to inject the USB3 drivers into Win7 install media. I suggest doing a search for any combination of Windows 7, USB, keyboard, drivers, etc. You're bound to find at least a handful of threads on the topic.
For starters, try here:
This message was posted on behalf of Intel Corporation
Thanks Det_Bradlee, M4rkytMark I suggest you to follow the steps on the thread that Det_Bradlee mentioned before to install windows® 7
Yes many thanks. I followed a number of the examples included in the original link and 2 or 3 others as well as intels own tool, but non worked for me.
Finally I was able to use another free tool called NTlite which allowed me to integrate the correct intel USB3 drivers into my WIN7 installation files and everything worked fine.