While USB 3.0 was delivered well after the PCI Express slot was introduced, many machines have a PCI Express 1x slot but it is covered by the video card and inaccessibles. The motherboard in our Acer E700 has two available PCI slots.
Some motherboards have a PCI Express x1 slot above the video card so USB cards or Wi-Fi cards could be installed.
There are a couple of models of PCI cards that can provide a USB 3.0 port for higher speed transfers. The Exsys EX-1093 offers 4 ports and it uses SATA power to provide the extra current needed for USB 3.0 devices.
Due to the power requirements its advisable to use a USB 3.0 powered hub to handle peripherals. USB 2.0 uses up to 500mA per port but USB 3.0 uses up to 900mA per port.
The extra power is useful mostly for older hard disks which used more power than the USB 2.0 ports could comfortably provide. We have a USB DVD drive which has a dual USB 2.0 cable to obtain additional power. The laser uses more power when it has to record data.
The USB 3.0 standard has much more bandwidth and PCI can handle a few ports before it saturates. PCI is capable of 133 MB/s and USB 3.0 has 5 megabit speed. PCI is fast enough not to saturate.
Unfortunately when USB 3.0 was released the PCI Express slot was already mature in the market place. So for those with older machines there are a few options but prices tend to be higher than the mass produced parts.
Startech also has PCI USB 3.0 cards. Startech specializes in components for older machines. Then tend to be expensive but the hardware does its job well.
Startech is readily available in the marketplace. Almost all major vendors have it.
The Exsys EX-1092 (2-port) or EX-1093 (4-port) may be harder to find but it has 4 ports making it a better choice.
None of the known PCI cards offer front panel connectors. The cards are all rear bracket style which augments the IO shield ports.
USB 2.0 cards are inexpensive but the faster USB 3.0 cards which is the focus of this article are available and installing one of them in an older box can make material improvements in its utility. For example, a USB hard disk can copy files 3-4 times faster than a USB 2.0 port can handle.