Specifications, Packaging, Internals, Testing Methodology and System Setup
Straight from Samsung:
Packaging is identical to that of the 840 series products from Samsung.
Breaking open the shells:
Note that the two smaller capacities go as far as using smaller PCBs. There is simply not a need for as many flash packages, so Samsung chose to go with a different PCB design as opposed to just leaving empty space on a board. The change in design also places the controller on top for some, and on bottom for others. I thought this might impact cooling, but a closer look at the thermal pads:
The pads are there, but we're not sure why, as they do not come into contact with any components of any of the PCBs. No component imprints are left in the material, and the machined standoffs suspend the PCB too far above the pad to make any sort of contact. Also of note was that there was no pad present on our initial 512GB sample, yet it was present on samples we received at a later date. Another fun fact – look at the marking on the inner part of the shell. Apparently there was no need to update the 840 EVO design. If it ain't broke…
Here are the fronts and backs of the PCBs:
We covered this a bit on the previous article, but now that we've been able to lay out all capacities, we can present a clear picture on die count staggering among the entire line. Here are the flash memory packages we found installed:
- K9LPGY8S1M – DDP (2 dies)
- K9HQGY8S5M – QDP (4 dies)
- K9PRGY8S7M – ODP (8 dies)
- K9PRGY8S5M – ODP (8 dies)
- K9USGY8S7M – 16 die stack
While the VNAND die capacity (86Gbit) is lower than the typical 128Gbit of 2D NAND, Samsung appears to be more adept at stacking it within a package, as we don't typically see 2D NAND at more than four dies per package, meaning higher capacity models of competing SSDs are forced to mount 16 packages on their PCBs.
The 'odd' die capacity means that to deliver the typical 2^n capacities that people are used to, Samsung had to stagger the package types. As an example, the 512GB 850 Pro needs 48 86Gbit dies. It accomplishes this with 4 QDP (4 die) packages and 4 ODP (16 die) packages. Other capacities perform the same trick, just with different staggering of package types. If Samsung were to keep with the typical uniform die counts per package, they could theoretically make the 850 Pro in capacities of 96GB, 192GB, 384GB, 768GB, and 1.5TB. Yes, 1.5TB could be possible in the current form factor, simply by using all 16 die stack packages, yielding 128 dies.
Our tests are a mix of synthetic and real-world benchmarks. PCMark, IOMeter, HDTach, HDTune, Yapt and our custom File Copy test round out the selection to cover just about all bases. If you have any questions about our tests just drop into the Storage Forum and we'll help you out!
Test System Setup
We currently employ a pair of testbeds. A newer ASUS P8Z77-V Pro/Thunderbolt and an ASUS Z87-PRO. Variance between both boards has been deemed negligible.
PC Perspective would like to thank ASUS, Corsair, and Kingston for supplying some of the components of our test rigs.
|Hard Drive Test System Setup|
|CPU||Intel Core i7-4770K|
|Motherboard||ASUS P8Z77-V Pro/TB / ASUS Z87-PRO|
|Memory||Kingston HyperX 4GB DDR3-2133 CL9|
|Hard Drive||G.Skill 32GB SLC SSD|
|Video Card||Intel® HD Graphics 4600|
|Power Supply||Corsair CMPSU-650TX|
|Operating System||Windows 8.1 X64|
- PCPer File Copy Test