Samsung 840 EVO 750GB Review
The Samsung 840 EVO 750GB is a tour de force in solid-state technology, combining for the first time vast capacity by ssd standards, with super fast performance, and at an approachable price.
The Samsung EVO is spearheads a second-generation of solid-state drive to use the more affordable TLC flash chips. It allows an increase in capacity and reduction in price. And a surprise when it comes to performance.
Samsung is still accelerating the development of flash memory, now introducing its second generation of TLC solid-state storage before any other brand has even shown its first.
For better performance and longevity, there’s still Samsung’s 840 Pro Series with its more familiar two-layer MLC technology. But we found that in performance terms at least, the Samsung EVO can hold its head up high against the 840 Pro; and with it, all current leading SATA 6Gb/s solid-state drives. [break][/break]
The use of TLC flash has here allowed a long-awaited extension in storage capacities. As well as the familiar sizes of 120, 250 and 500GB, Samsung has added 750GB and 1TB sized drives.
[break][/break] The latter becomes the first truly terabyte SSD, since Crucial’s competing flagship M500 series includes additional built-in over-provisioning that brings the available space on its largest SSD to just below the terabyte mark, at 960GB. [break][/break] Recommended prices for the Samsung 840 EVO Series SSDs start at £86.99 for 120GB, then £148.99 for 250GB, £289.99 for 500GB, £415.99 for 750GB and £509.99 for 1TB. [break][/break]Samsung 840 EVO 750GB: Super fast
The buffer size is relatively large, so that with most daily operations it should not be readily depleted. But if it is, it simply puts write operations back to regular TLC speeds. For reference, the original 840 Series with its unaided TLC flash had sequential write speeds of around 250 MB/s.
[break][/break] Since this dedicated part of the drive only works in SLC mode, Samsung assures us it will have better endurance than short-lived TLC – around 100 times longer life.The two smallest drives each get 3 GB of TurboWrite Buffer, while the 500, 750 and 1000 GB capacity versions get 6, 9 and 12 GB respectively of fast-write buffer. [break][/break]
Samsung 840 EVO 750GB: Other changes
Besides some clever data juggling used to bolster write speed, several other changes have been noted for the Samsung 840 EVO when compared to the original 840 Series.
The controller is now designated MEX rather than MDX, still based on a three-core ARM processor and with clock speed increased from 300 to 400 MHz. This is said to assist in management of the larger capacities, as well as deal with the shift to a new 19nm NAND process.
The controller is backed by more DRAM cache for the largest drives, taking 256 MB cache for the smallest 120 GB capacity, 512 MB again for the 250 and 500GB models; and now featuring 1 GB of LPDDR2 memory for the 750 GB and 1 TB capacity SSDs.
Idle power consumption is said to be reduced, while temperature sensing deliberately slows the drive down when it gets too hot under load. Dynamic Thermal Guard looks like a similar technology to the adaptive thermal monitoring used in Crucial’s latest M500 series SSDs.
Samsung 840 EVO 750GB: Performance
When we first tested the Samsung 840 EVO, we were almost downcast to find comparable performance to the previous-generation Samsung 840 Pro. But we were not immediately aware of the technology inside, based on TLC flash like the cheaper 840 Series; not 2-bit MLC like the 840 Pro Series. Things were looking interesting again.
[break][/break]Looking at the other extreme, of very small files, we found that 4 kB random reads had just about doubled in number, from 22 to 41 MB/s with the 840 EVO.
That’s with a single queue, a good indicator for real-world performance still, as your PC spends a lot of time working randomly with many one-off small files, not just large sequential transfers or even multi-threaded small random read/writes.
Increasing queue depth to QD=32, the 840 EVO also approached its Pro-labelled mentor. Random 4 kB reads now hit 405 MB/s and writes were 367 MB/s. Which means the 850 EVO is now officially in the 100,000 IOPS league with its 104k IOPS read result.