In September, Samsung acknowledged widespread user reports of performance issues with its 840 EVO range of solid state drives and that it was working on a fix. Now it's come good on its word, releasing a utility to address the problem, but only for specific setups.
Specific, in this case, should cover most owners — the tool is Windows only, requires the drive be formatted with NTFS and that at least 10 per cent of the drive's capacity is free space. The first two conditions rule out Linux and Mac users, who will have to wait a bit longer for a fix (and even then it'll be for DOS), according to Anandtech's Kristian Vättö.
The reason the firmware can't be flashed and the whole thing forgotten about is because the bug is related to "old" data, so to get the drive back in peak condition, it needs the tool to render some currently undisclosed magic on the SSD.
On a related — and troubling — note, the Anandtech story states the problem could affect the plain 840 as well, though Samsung hasn't seen this for itself and has no plans to provide a utility for those affected.