Samsung's 840 SSD is the first drive on the market that uses TLC flash memory. In our testing, we see decent performance that is 10% below that of modern SandForce-based drives and 20% below the fastest drives in our test group. Compared to the higher-end Samsung 840 Pro, which uses MLC memory, the difference is 15%. While those numbers sound like the 840 non-Pro will be a lot slower, performance really depends on the kind of workload. Low-write loads barely see any performance difference to other drives. The 840 is also very fast when only relatively small amounts of data are accessed. Due to the TLC design, the biggest performance loss comes in write-heavy applications that require lots of sustained throughput which is not that relevant for typical consumer workloads. In our MySQL enterprise testing, this shortcoming is very apparent though, making the 840 the slowest drive in this benchmark.
In our steady state performance testing, we see results similar to that of SandForce drives, which is quite alright. Drives using the latest technology, like the Corsair Neutron and OCZ Vector, do much better here, but steady state performance is really a borderline test-case with more scientifical than real-life value for typical consumer workloads.
The highlight of the Samsung 840 is clearly its amazing price: the 250 GB version is currently available for $190, which makes it the most affordable drive out there when considering price per GB—thanks to its TLC flash chips. When looking at performance per dollar, the 840 also delivers top results and is only beat by the newly released Crucial M500 (full review coming soon).
If you are in the market for a cost-effective SSD solution and don't want to pay a premium for the highest performance, which may or may not make a noticeable difference in day-to-day use, then the Samsung 840 should definitely be on your short list.