I have the Antec 302 case and it has 2 x USB 3.0 front ports on the case.
If I get a Mobo that doesn't have an onboard 3.0 (Only 2.0) does that mean I can't use these at all, or that they will simply run at downgraded speed of 2.0 instead?
Wasn't sure if the plug in connection is the same or not.
Sorry, but u couldn't use them. USB2 and USB3 headers are not compatible.
And there is no adapter also.
So, yes, those front USB3 ports are not going to be used at all.