We're all familiar with the 2.5" Serial ATA SSDs that Samsung makes available to end users. They're not the only drives in the company's stable, though. Samsung also has a line of PCI Express SSDs reserved for big PC vendors. These drives typically aren't sold in the channel, but they can be found inside select systems, and some of them are pretty sweet. Here are a few we spotted at Samsung's SSD Global Summit in Seoul, South Korea last week.

The beast pictured above is the SM1715. It has a four-lane PCI Express 3.0 interface, and like most new PCIe drives, it uses the SSD-specific NVM Express protocol. Samsung says the half-height, half-length version is available in capacities up to 3.2TB. That drive can hit 750k IOps with random reads, the company claims, and 180k IOps with random writes.

In addition to being available on an expansion card, the SM1715 comes in 2.5" form. That variant has the same four-lane PCIe link, this time routed through an SFF-8639 connector.

Like its card-based sibling, the 2.5" version is rated for 750k random read IOps. The random write spec is pegged at only 115k IOps, though, and the peak capacity is 1.6TB. Odds are the lower random write rate is related to the lower maximum capacity.

The 2.5-incher is selling in Dell's PowerEdge R920 server, where it appears to have been rebranded as the "PowerEdge NVMe Express Flash PCIe SSD." I don't see any listings for the card-based version, though.

The other drive worthy of note is the XP951, which is the successor to the XP941 released last year. This client-oriented model upgrades its predecessor's PCIe Gen2 x4 link to Gen3 speeds, but it's not fast enough to keep up with the server SSDs. Sequential throughput peaks at 1.6GB/s for reads and 1GB/s for writes, according to the official specs, while random I/O is rated at 130k/100k IOps.

Samsung says the XP951 is "coming soon" in M.2 and 2.5" flavors. The drive will likely appear in next-gen ultrabooks, but if you want to buy it separately, you'll probably have to scour eBay. Samsung doesn't appear to have any plans to make the XP951 available at vendors like Amazon and Newegg.