Some devices don't like Intel's current USB 3.0 in desktop chipsets (I don't recall if Broadwell mobile has updated ones). Most such devices work fine with Renesas/NEC USB 3.0 controllers, though, so will likely work fine with newer controllers from Intel (don't know that, but it seems likely, given their roadmaps, and that users don't like replacing working peripherals). They tend to be keyboard, trackpad, and mouse controllers. My USB->PS/2 dongle, FI, doesn't work with USB 3.0 on the 7-series.
Your new computer more than likely has the 2 USB 3.0 ports due to chipset cost, though having one or two non-3.0 is often done even if not necessary, due to rare compatibility issues.
If you have the slot spare, a 4-port Renesas-based card would be a solid addition. Some storage devices can get a bit faster with Asmedia chipsets, but Renesas has compatibility going for it, and can still do well enough to saturate most drives, and the lone PCIe lane it's on, even so.
However, you cannot convert 2.0 ports to 3.0, only add them. So, if you want more front USB 3.0 ports, you'll need to get a card with a header, and 3.5" or 5.25" bay device(s).