Samsung 750 EVO 120GB and 250GB 2.5" SATA SSD Full Review - The Return of 2D NAND
Introduction, Specifications and Packaging
The steady increase in flash memory capacity per die is necessary for bringing SSD costs down, but SSDs need a minimum number of dies present to maintain good performance. Back when Samsung announced their 48-layer VNAND, their Senior VP of Marketing assured me that the performance drop that comes along with the low die count present in lower capacity models would be dealt with properly. At the time, Unsoo Kim mentioned the possibility of Samsung producing 128Gbit 48-layer VNAND, but it now appears that they have opted to put everything into 256Gbit on 3D side. Fortunately they still have a planar (2D) NAND production line going, and they will be using that same flash in a newer line of low capacity models. When their 850 Series transitions over to 48-layer (enabling 2TB capacities), Samsung will drop the 120GB capacity of that line and replace it with a new OEM / system builder destined 750 EVO:
The SSD 750 EVO Series is essentially a throwback to the 840 EVO, but without all of the growing pains experienced by that line. Samsung assured me that the same corrections that ultimately fixed the long-term read-based slow down issues with the 840 EVO also apply to the 750 EVO, and despite the model number being smaller, these should actually perform a bit better than their predecessor. Since it would be silly to just launch a single 120GB capacity to make up for the soon to be dropped 850 EVO 120GB, we also get a 250GB model, which should make for an interesting price point.
Baseline specs are very similar to the older 840 EVO series, with some minor differences (to be shown below). There are some unlisted specs that are carried over from the original series. For those we need to reference the slides from the 840 EVO launch:
Our initial review of the 840 EVO was limited to the sampled 500GB and 1TB capacities, but this time we need to pay attention to the smaller figures. The 250GB model is still able to saturate SATA with its TurboWrite buffer, despite having a slower rated TLC speed of 270 MB/s. The further reduction in available dies of the 120GB model reduces those figures to 410 MB/s for cached writes and 140 MB/s for sustained transfers overflowing the SLC cache. Speaking of cache:
Despite the capacity difference, both the 120GB and 250GB models come equipped with the same generous 3GB of TurboWrite cache.
The bracketed  numbers above are from the 850 EVO, which uses more efficient / faster 3D VNAND. Since the planar NAND used here was launched prior to that newer technology, it does not see the same power efficiency and endurance benefits. That said, 6mW DEVSLP is still nothing to sneeze at, and such a small draw has a near negligible impact on mobile standby / idle battery drain.
Remember, Samsung is marketing the SSD 750 as an OEM / system builder drive. Our samples arrived without packaging, but Samsung passed this image along for us to include in the review:
OEMs would be ordering these on bare trays, but this will likely be the system builder / 'white box' packaging. This is the same familiar packaging seen over the last several generations of Samsung SSDs.