If you want to add USB 3.0 devices to your system and get the performance and other benefits they provide, you first need to add USB 3.0 ports to your system. For this there are several different ways this can be achieved.
An Add-on Card for Desktop Computers
Adding USB 3.0 ports via an add-on card is often an easier and less expensive than replacing the motherboard or buying a new computer. To upgrade a desktop computer to USB 3.0, you must have an accessible PCI Express (PCIe) slot that’s x1 or wider.
PCIe x1 cards are available from several supplies together with PCIe x4 cards that provide both USB 3.0 and eSATA 6GBps are currently available.
Be sure to check the following issues when you compare these cards:
1. Bracket types provided—if you are planning to install a USB 3.0 card into a system that uses shorter-than-normal card brackets (such as a low-profile or home theatre PC); make sure you choose a card that includes a low-profile bracket.
2. Auxiliary power requirements—Many cards use a four-pin hard disk (Molex) power connector, while others use a four-pin floppy power connector, an SATA power connector, or a USB motherboard header. Dependent upon your power supply or motherboard design and drives in use, you might need to use an adapter or a splitter to deliver power to your card.
3. Version of PCIe supported—to get the maximum level of USB 3.0 performance, make sure your card supports PCIe version 2.0 or greater. PCIe version 2.0 supports twice the bandwidth of PCIe version 1.0, and most recent motherboards support PCIe version 2.0 (check your motherboard/system documentation if you’re not sure).
PCIe x1 versus x4—almost all of the PCIe cards for USB 3.0 use the x1 expansion slot, which means they can fit into x1 or wider PCIe slots (x4, x8, x16). Thus, they can be used in any PCIe motherboard. Unfortunately, a PCIe x1 slot cannot provide full presentation for even a single USB 3.0 port.
The bandwidth of a PCIe x1 slot is 250MBps in version 1; most recent motherboards support PCIe version 2, which doubles each lane to 500MBps.
Consequently, a single USB 3.0 device saturates the bandwidth of a PCIe x1 v2.0 slot, and two USB 3.0 devices (all USB 3.0 PCIe cards have two ports) receive only 250MBps each on a system running PCIe version 2 slots and a PCIe version 2 USB 3.0 card, and just half that if running on PCIe version 1 hardware.
These features appear to make a PCIe x4 USB 3.0 card which also offers a couple of eSATA 6Gbps ports more attractive from a performance side of things. However, there’s still more to consider before you decide to get one.

Does your computer have any available PCIe x4 or wider slots? Many do not. Although you can use a PCIe x16 slot for the card, using an x16 slot might prevent your being able to run SLI or CrossFire dual graphics cards, especially on a motherboard using an Intel chipset. Note that some new motherboards use the x16 form factor for slots that have x8 or x4 connectors. Review the motherboard’s documentation to see the actual PCIe lanes supported in each slot.
Does your motherboard have enough PCIe lanes to support the card and other PCIe devices you have installed (such as a second PCIe x16 card for SLI or Crossfire)? Some motherboards feature PCI Express 2.0.0 lanes mainly for graphics and PCIe v1.0 lanes (which run at half the speed of v2.0) for I/O cards. If you use dual graphics cards (NVIDIA SLI or ATI/AMD Crossfire), the motherboard must use the PCIe v1.0 lanes for your card, reducing performance. If you plan to use the SATA 6Gbps interface, do you really need it? The only drives currently on the market that require the full performance of SATA 6Gbps are some late-model SSDs. If you’re running mechanical hard disks, SATA 3Gbps is more than fast enough for now.