With so many SSD manufacturers jumping aboard the SandForce 2281 bandwagon, competition is becoming increasingly fierce, especially as every company is set on carving out a piece of lucrative SSD pie. ADATA is the latest entrant onto the market, with its S511 range of SSDs looking to offer the most affordable route to the SandForce 2281’s 500MB/sec read speeds.
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As we’ve seen with the OCZ Agility 3 240GB, using a SandForce 2281 drive controller doesn’t always mean super-fast performance. In the case of the Agility, this was due to its use of asynchronous NAND, which saw incompressible data performance suffer dramatically. The S511 uses synchronous 25nm Intel NAND, like the OCZ Vertex 3 240GB, with 16 Intel 16GB NAND modules fitted to its PCB for a total of 256GB. As we found with the Patriot Wildfire, using fancy and expensive 32nm NAND alongside the SandForce 2281 controller doesn’t produce much more speed, so the 25nm synchronous option looks to be the sweet spot.
However, as with all SandForce-based SSDs, the S511 is over-provisioned to make room for SandForce’s on-board error-correction system, and to allow for continued operation should any of the NAND fail. This is the reason that the drive's capacity is advertised as 240GB rather than 256GB, and why it boasts a formatted capacity of 224GB; 14 per cent of the available NAND is reserved for over-provisioning.
This over-provisioning allows storage to be set aside for SandForce’s DuraWrite compression technology. This is the key to the drive controller’s high performance, as its on-the-fly compression enables it to write less data than the operating system originally gives it, reporting back the effective (and usually very high) speeds.
However, this system also means that when handling data that’s already heavily compressed, such as images, videos and many game and software files, the drive operates at a much lower speed than the best-case maximum. With quoted speeds of 550MB/sec for sequential reads and 520MB/sec for sequential writes, the S511 matches many competing SandForce 2281 drives for claimed performance.
A SandForce 2281 drive controller and Intel NAND power the S511
While the S511 might be identical in its drive controller, NAND and formatted capacity to the Vertex 3, its biggest advantage is its price. At £331 (£1.48 per gigabyte), it’s by far the best-value SandForce 2281-based drive we’ve seen.
However, over the past few months the price of the competing Marvell-based Crucial M4 256GB has dropped massively to just £280 (£1.13 per gigabyte), so the S511 is still considerably more expensive per gigabyte. The M4 is now a much more serious performance competitor too, thanks to its latest 0009 firmware unlocking a great deal of extra performance.
Despite the similarities in terms of hardware, however, the S511 is unlikely to perform identically to the Vertex 3 240GB due to the different firmware versions of the drives. Our results are based on the 319ABBF0 firmware of the S511 and the latest v2.11 firmware of the Vertex 3.