This is our second round of testing with Samsung's Ultra M.2 PCIe-based XP941 enthusiast / prosumer SSD. In round 1, we tested the 512GB model and found it to be an amazing performer, but we also found why Samsung reserved this model for limited distribution and OEM systems - heat output.
The performance can be summed up in one word, amazing. With nearly 1200 MB/s of sequential read performance, end users can achieve higher than two-drive RAID 0 SATA performance, with less power and component space. We've demonstrated that 4K video at high bit rates requires more than 700 MB/s for buffer free playback, working with 4K video requires a bit more to edit in real-time. Work aside, it's fun having the fastest storage available. Your games load faster so you can get in multiplayer before others, and your file transfers are faster. Since your storage device is the slowest component in your system, anything you do to increase storage performance has a noticeable effect on your computing experience.
When we tested the XP941 512GB drive provided to us by RamCity a few months back, we needed an adapter to run the drive in our system. A short time after the review we received an ASRock Z97 Extreme 6, the first consumer motherboard with support for Ultra M.2. Then we went to Computex in Taipei, and while at the show, we found a number of new motherboards, based on the new X99 chipset, packing Ultra M.2 slots. Above we see a marketing image of MSI's X99S SLI Plus motherboard. When you zoom in, it's easy to spot the M.2 socket between the second and third PCIe x16 slots. Zooming in further we see the slot is labeled M.2 x4.
That means the slot uses at least PCIe 2.0 x4, or four lanes of PCIe bandwidth. We say at least PCIe 2.0 because there are rumors of PCie 3.0 x4 coming on some motherboards, the same configuration ASRock used on the Z97 Extreme 6. As mentioned, at Computex we spotted a number of next generation X99 motherboards with M.2 motherboards with four PCIe lanes dedicated to storage. The current rumor is X99 motherboards should hit the market on August 29 2014 with PCIe based M.2 in tow.
Investing in Intel's latest HEDT platform for enthusiast and prosumer users will be a costly endeavor. The Haswell-E based system requires a new processor, motherboard and DDR4 DRAM. There's no shame in looking for ways to trim the initial cost. We suspect most new HEDT platform users will want to take advantage of M.2 storage capabilities and the cheapest way to do that is with the Samsung XP941 128GB SSD.
Specifications, Pricing and Availability
The XP941 hit the market after Samsung's 840 Pro and EVO products. It uses a PCIe to flash controller with three cores, named UAX. The drive arrived before Samsung released the 850 Pro, so it still uses 2D planar NAND, but we wouldn't be surprised to hear about a 3D V-NAND model this time next year.
In the image above provided by RamCity, we see a comparison between the 840 EVO, 840 Pro and XP941. It's easy to spot where the XP941 pushes past the 840 Series products. Sequential read and write performance is substantially higher as is 4K random read IOPS.
The performance increase is made possible by the interface used. The M.2 socket can use both SATA and native PCIe signals. PCIe based M.2 offers up to 32Gb/s of bandwidth when configured with PCIe 3.0 and four lanes. The XP941 doesn't reach the maximum possible speeds since it's based on PCIe 2.0, but it still outperforms SATA by a large margin.
Today, we're looking at the 128GB model from the XP941 product family. Our sample was provided by RamCity and they are also one of the few resellers to carry the 128GB capacity size. Sadly, the 128GB stock has sold out at the time of writing, but stock should arrive before the end of the month. At this time, RamCity has stock of the 256GB and 512GB models.
Prices at the time of writing come out to $487 (512GB), $279 (256GB) and $169 (128GB), all prices in USD. RamCity is based in Australia, but our sample arrived the same week we ordered.
The XP941 128GB is a little slower on paper than the two larger capacity sizes. RamCity specs the drive at 1000 MB/s sequential read, 450 MB/s sequential write, 110K random read IOPS and finally 40K random write IOPS. Your mileage will vary based on the motherboard used since PCIe bandwidth is dependent on the PCIe configuration used by the motherboard manufacturer.