Crucial's M500 SSD range is one of only two to offer an as-near-as-damn-it 1TB capacity option, along with Samsung's SSD 840 Evo range. Both also target mainstream audiences more than pure performance hunters (if you can call £500 for an SSD mainstream). As such we're keen to see just how the two stack up.
Today we're looking at the 480GB M500, but it has the same top end specs as the 960GB drive, namely 500MB/sec and 400MB/sec claimed sequential read and write speeds and 4K random performance of 80,000 IOPS.
Like many modern SSDs, the M500 is a 7mm tall drive and comes with a spacer for it to fit 9.5mm mounts. The aluminium exterior is nice, adding a slightly premium feel, although the drive is still rather light and it doesn't quite have the allure of the Evo's grey and black finish. Opening everything up is a simple process thanks to a set of Philips screws, and doing so reveals a large thermal pad that covers the controller and DRAM. The aluminium chassis is thus used to dissipate heat, and the controller will throttle performance if temperatures become too toasty; a feature shared with the Evo as well. Of course, opening the drive up will void your warranty.
Click to enlarge
This SSD's predecessor, the M4, came out more than two years ago now, so it's not surprising to see changes to each of the main components. First up, the NAND. The M500 is the first SSD to make use of IMFT's 128Gbit 20nm MLC NAND dies. Specifically with the 480GB drive, you'll find 16 NAND packages each containing two such dies. The high density of this flash is what allows Micron to hit a relatively low cost per gigabyte. In theory, its endurance should be higher than the TLC NAND in Samsung's Evo drives due to it only storing 2 bits per cell rather than three, although both companies offer the same three year warranty.
Controller duties are handled by Marvel's 88SS9187, which features eight channels and a speed boost over the previous generation. The custom firmware that keeps everything running has also seen a range of upgrades to improve performance and to match it to all the new hardware.
Click to enlarge - The Marvell controller is paired with 512MB DDR3 cache and 16 NAND modules
The controller also now supports DDR3 memory, and as such you'll find a 512MB DDR3 DRAM cache in the 480GB drive, with other capacities sporting different amounts. There is apparently less than 5MB of actual user data in the DRAM at any one time, with the rest reserved for page mapping. The array of capacitors on the PCB is used to power the drive for a split second in the event of a power failure, giving the drive time to flush everything currently in the cache to the non-volatile NAND, which is a really neat feature.
As well as 256-bit AES encryption, the M500's controller is compliant with the TCG Opal 2.0 and IEEE-1667 standards. This means the SSD is compatible with Microsoft's eDrive protocol in Windows 8, such that BitLocker can bypass the need for the software encryption that's usually used. The short story is that encrypting your drive in this hardware accelerated way should be quicker and less draining on system resources and power consumption.
Click to enlarge - The series of capacitors here are used to protect against data loss in the event of power failure
Despite the 512GB of raw NAND in our M500, it's sold as a 480GB model. Rather than this simply being a case of more over-provisioning than we're used to, it's actually due to RAIN (Redundant Array of Independent NAND), whereby the uncounted portion of NAND is reserved for data redundancy. While it doesn't provide the same level of redundancy as a full RAID set-up, it's still a good step taken against NAND cell failures. With a usable capacity of 447GB, the M500 also has a standard 7 percent or so of its NAND set aside as spare area.
Interface: SATA 6Gbps Nominal capacity: 480GB Formatted capacity: 447.13GB (~6.8 percent over provision) Controller: Marvell 88SS9187 Cache: DDR3 512MB Memory type/amount: 16 x 32GB Micron 20nm MLC NAND Warranty: Three years