If your PC lacks a SATA 6-gigabits-per-second interface, you can't get top performance out of any of the latest consumer-grade solid-state drives. Such drives bump up against the 6-gbps limit of that bus, while the older second-generation SATA interface maxes out at just 3 gbps. Apricorn's Velocity Solo x2 should remove that roadblock for you. See all storage reviews.
My main system sports a circa-2009 Intel D58SO motherboard. It has a great feature set, but it predates third-generation, 6-gbps SATA. The only way to upgrade such a beast is via a PCIe adaptor card with a SATA 6-gbps interface, of which the market has plenty to choose from. I tried installing one of those a couple of years ago, but it gave me blue screens. SSDs at that time weren't nearly as fast as they are today, so I saw no real reason to upgrade. But with SSD performance now topping 600 MBps, it's time.
Velocity Solo X2: PCIe cards
Lo and behold, Apricorn contacted me about its Velocity Solo PCIe cards. These will not only add SATA 6-gbps capability to any system with an available PCIe slot, but they'll also serve as a caddy for a single SSD. Apricorn sent two cards for me to evaluate: the Velocity x1 and the £79 Velocity x2. I tried both, and recommend one.
A Kingston HyperX 3K drive attached to my motherboard's second-generation SATA interface, which is capable of delivering maximum performance of only 3 gbps, read data at 227 MBps and wrote data at 236 MBps while running the synthetic benchmark CrystalDiskMark 3. Surprisingly enough, a much faster OCZ Vertex 4 SSD mounted on the Velocity x1 delivered slower performance: It read at only 203.3 MBps and wrote at 196.5 MBps.
When I paired the Vertex 4 with Apricorn's Velocity Solo x2 card, however, the SSD's numbers jumped to 348.1 MBps reading and 323.2 MBps writing--a substantial improvement beyond what is possible with the second-generation SATA interface. Attaching the Kingston HyperX Max to the Velocity Solo x2, meanwhile, improved its numbers to 322.1 MBps reading and 239.6 MBps writing. That considerably faster read performance made my system feel much more responsive.
Velocity Solo X2: difference in performance
The reason for the two cards' performance disparity is that the x1 uses only a single PCIe 2.0 lane, while the x2 employs two lanes (and must be installed in at least a PCIe 2.0 x2 slot as a result). Since each PCIe 2.0 lane is capable of transferring data at 500 megabytes per second (or 3.9 gigabits per second) in each direction, two PCIe lanes are necessary to satisfy the requirements of the SATA 6-gbps interface. Both Velocity Solo cards are outfitted with a standard female SATA connector for attaching a second drive, and both cards are bundled with Apricorn's EZ Gig software for cloning your existing hard drive to your new SSD.