One thing that has remained pretty constant since SSDs
started to appear, is that the storage interface they connect to appears to
struggle to keep pace with the performance levels of the SSD.
The SATA2 interface was soon saturated by the SSDs of the
day, and SATA3 hasn’t done much better. If we look at mainstream PC platform
chipsets such as the Intel Z68, Z77, Z87, and now Z97, they all have one thing
in common. You have the high speed ‘north’ side of the board where the CPU,
memory, and PCIe3 reside. PCIe3 connects direct to the CPU, and has 16 10Gbps
lanes available for graphics cards or PCIe storage.
The ‘south’ side of the board where the platform controller
hub (PCH) sits is very much slower, and restricted to PCIe2 speeds. In actual
fact you have 8 PCIe2 lanes with 5Gbps bandwidth per lane. The PCH not only
hosts the SATA interface but also all the other connected peripherals that are required
in order to allow the PC to function, such as LAN, USB, and audio.
The Intel Z97 chipset supports M.2. and SATA Express
natively, but uses only two PCIe2 lanes, and these are shared between M.2. and
SATA Express, and have a maximum bandwidth of 10Gbps. That would give up to
1GB/s available bandwidth without overheads. With overheads that will drop down
to around 780MB/s, which isn’t a vast improvement over SATA3 speeds. Nevertheless,
that is all that’s available via this revision of the PCH on Z97. It is
rumoured that the Intel 100 series chipset, designed for the Intel Skylake CPU
will make the transition to PCIe3 for the PCH, which will double the amount of
available bandwidth at the ‘south’ side of the board, but Skylake is more than
a year away.
It could be that to properly support future SSDs, the
storage interface will have to move to the ‘north’ side of the board. This
seems quite simple, you can use one of the PCIe3 x16 sockets for a PCIe SSD
such as the OCZ RevoDrive 350, or wait until NVMe SSDs start to appear in
mainstream form. The problem with this approach in a mainstream PC is the fact
that PCIe3 is generally used for graphics cards, and I can’t see gamers giving
up graphics bandwidth for storage, plus you only have 16 PCIe3 lanes available.
With the next generation of CPUs dropping to a 14nm
fabrication process, that will give more room on the CPU die for more
components, and it would make perfect sense to me for Intel to add a high speed
storage interface to the CPU itself. This won’t happen with Broadwell, and from
what I know about Skylake it won’t happen there either. So that leaves PCIe3,
M.2., or SATA Express for the immediate future.
That neatly brings us to the point of this article. In this
review I will be checking out an M.2. PCIe SSD in the shape of the Plextor M6e
M.2., which Plextor very kindly sent me for review. In fact I’ll be looking at
the 256GB version of the M6e M.2.. Also available are 128GB and 512GB versions.
So let’s find out how this new SSD performs in our range of
Plextor company information
Plextor should need no introduction, but those of you who
would like to find out more about Plextor, can do so at their website.
The Plextor M6e M.2. 256GB SSD
Now it’s time to take a look at the drive itself and what it
came shipped with.
Plextor M6e M.2. Pro SSD package
The M.2. SSD I received was already mounted on a PCIe
adapter. The M6e M.2. was removed from the bracket for most of the tests.
Now let’s head to the next page, where we look in more
detail at the Plextor M6e M.2. 256GB SSD…..