Installing Windows 7 x64 on a computer with only USB 3 ports

I am installing Windows 7 x64 on a HP EliteDesk 800 G3 SFF that only has USB 3 and USB Type-C ports.

Initially, upon booting the USB install media, the USB keyboard and mouse wouldn't work - this was because the Windows 7 install media doesn't have USB 3 drivers.

I was able to modify my Windows 7 install media (USB drive) by using DISM to include the USB 3 drivers. Following this guide, I downloaded the USB 3 drivers from HP's website and extracted the driver files and embedded them onto the USB install media. I was then able to install Windows 7 successfully.

However, after Windows 7 x64 is installed, I get stuck at the setup screen because the USB keyboard and mouse don't work again - this is because the USB bootable install media had the drivers on it but they weren't installed when the OS was installed so I am stuck with a computer that has Windows 7 installed without USB 3 drivers so I cannot complete the initial Windows setup.

The drive Windows is installed on is a M.2 SSD.

I also checked the BIOS and there is no way to disable USB 3.

Is there a way to modify the bootable USB media so that it not only runs the USB 3 drivers but also installs them with the OS so I can use them after Windows is installed?

Or is there another way to do this?

Related issues: 1, 2, 3.

I successfully installed Windows 7 on a laptop with a USB 3.0 root hub by using NTLite.

It will allow you to insert the USB 3.0 driver inside your Windows 7 ISO.

NB: You don't need to buy a license for NTLite, the free version is enough for this use.

There is a tool for exactly this case supplied by intel. It slipstreams the drivers into the installation media in a way that it will also work once installed (I only tested it with an EliteDesk 800G2 SFF but I doubt it has changed that much). Be careful to chose the right version to download, there is a different one for Win7 and Win8 or higher.

Also the tool is a little finicky, you really have to have the image on a usb drive it can not be unpacked into a folder for some reason.

EDIT: As it seems intel removed their own tool because it did not work all the time. They now recommend to use a tool by gigabyte in cases where PS2 devices do not work. It can be found on this page and is named Windows USB Installation Tool. I have no experience with this tool but it is the official recommendation at the moment.

An alternative to injecting drivers is checking your UEFI/BIOS for a legacy USB mode.

This, as I understand it, presents the peripherals directly to the operating system (perhaps as if they were plugged in via ps/2). Once windows is fully installed, you should be able to go back into BIOS and disable that option.

This question has more information on this mode; What does "Legacy USB Mouse" support in a BIOS mean?

Besides using DISM to integrate the drivers into BOTH boot.wim and install.wim (as Xyf already posted) there is another trick that usually works:

During the Win7 setup there is the possibility to load extra drivers (to get extra mass-storage drivers on-board).
What most people don't realize is that this can load other drivers too as long as they are suited for whatever hardware is in the system.
And drivers loaded at this point will automatically be installed to the new OS.

It isn't guaranteed to work (I have never been able to establish exactly what makes a driver work or not at this point) but it is certainly a lot quicker than a second session with DISM if it does happen to work.

From the specifications:

Front: 
    1 SD 4 card reader (optional);
    1 USB Type-C™; 
    2 USB 3.1 Gen 1; 
    1 USB 2.0; 
    1 USB 2.0 (fast charging); 
    1 Headphone connector; 
    Universal audio jack with CTIA headset support
Back: 
    1 audio line in; 
    1 RJ-45; 
    1 power connector; 
    1 audio out; 
    2 DisplayPort™; 
    2 USB 2.0; 
    4 USB 3.1 Gen 1; 
    3 optional ports

It appears that your machine should have USB2.0 ports. I would use them.

If not, can you get inside the machine? It will probably still have the USB2.0 headers internally, and you can use a cheap adaptor like this one to connect your keyboard for the installation process.