Internals, Testing Methodology and System Setup


Not much to take apart here, but I'll do what I can:

With the stickers removed, we can see the controllers and flash. The XP841 (top) and AHCI SM951 (bottom) have similar component counts (when you consider components mounted on the top and bottom of the PCB), save two additional flash packages on the 512GB unit. The center position is held by the NVMe version of the SM951, which fits all components neatly onto the front side of the PCB.


To summarize what we detailed back in the P3700 articleNVMe is a new protocol that replaces the dated AHCI stack. Similar to how Directx 12 reduces CPU overhead for graphics calls, NVMe reduces CPU overhead for storage IO calls. This is necessary in order to get SSD performance past the limits of the older protocol. Without it, SSDs capable of high IOPS would also require many CPU cores fully saturated to support them. NVMe eases that bottleneck, along with some great bonuses in the form of reduced latency oer IO.

Testing Methodology

Our tests are a mix of synthetic and real-world benchmarks. 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 have several storage testbeds. A newer ASUS P8Z77-V Pro/Thunderbolt and an ASUS Z87-PRO. Variance between both boards has been deemed negligible when testing SATA devices. Future PCIe and SATA device testing, including this review, will take place on a new ASUS Sabertooth X99, which comes equipped with USB 3.1, M.2, and can also handle SFF-8639 devices with the proper adapter.

PC Perspective would like to thank Intel, ASUS, Corsair, Kingston, and EVGA for supplying some of the components of our test rigs. 

Hard Drive Test System Setup
CPU Intel Core i7 5820K @ 4.125 GHz
Motherboard ASUS Sabertooth X99
Memory 16GB Micron DDR4 @ 3333
Hard Drive G.Skill 32GB SLC SSD
Sound Card N/A
Video Card EVGA GeForce GTX 750
Video Drivers GeForce Game Ready Driver 347.88
Power Supply Corsair CMPSU-650TX
DirectX Version N/A
Operating System Windows 8.1 Pro X64 (update)
  • PCPer File Copy Test
  • HDTach
  • HDTune
  • IOMeter
  • YAPT
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