Does that apply to just G27 wheels or all wheels should be connected to USB 2 only?
I'm not sure to be honest; this is from one the stickies on their support forum:
- if you miss the resolution menu in the video options, try to opt in of beta Steam client, let Steam downloads the new client, then opt out again
- Rename your "Assetto Corsa" folder located inside "My Documents" Windows folder;
- Remove any python addon apps you've installed;
- Run a Steam cache integrity check for Assetto Corsa;
- Launch the game and reconfigure all the options from scratch.
Usually, this fixes the most common issues users are facing.
In some scenarios, unsupported or misconfigured 3rd party software could be the causes. Try the following:
- Check that your controller is plugged in a USB2 port (don't use USB3)
- Update/reinstall graphics card drivers and directX software
- Update VS Runtime:
http://www.microsoft.com/en-us/download/details.aspx?id=40784
- Update/reinstall Microsoft .NET:
http://www.microsoft.com/en-us/download/details.aspx?id=42642
- Close any video overlay sofware (VirtuMVP, Fraps, XFire, MSI Afterburner, Rivatuner and similar);
- Double check CPU and GPU temperatures.
- Check Windows user's privileges (set Steam and Assetto Corsa with admin rights)
- Temporarily shut down any antivirus or firewall (or allow acs.exe and assettocorsa.exe files);
It doesn't mention specifics so I can only assume that's a blanket approach to all controllers/peripherals.