I'm in the market for a new motherboard that has USB 3.0 support, and I've been looking at some that have Intel's Z77 chipset. The specs for the Z77 explicitly state that only 4 USB 3.0 ports are supported, but a lot of the motherboards that I'm looking at with Z77 chipsets have 6 USB 3.0 ports (4 in the back, 2 in the front), so I was wondering what would happen in this situation. Would some of the ports be automatically disabled, would they be treated as USB 2.0 ports, or would they all just have reduced (yet still faster than USB 2.0) speeds?
Only four ports are native. The others are driven by third-party or non-Intel drivers like Marvell or JMicron. Non native ports are usually cursed with wonky performance so hook up all your SSDs and such to the native ports for the best speeds.