NVMe SSD Results
NVMe (Non-Volatile Memory Express) is the future of storage. Intel started developing the protocol for next-generation 3D XPoint technology. For now, most NVMe devices use PCIe 3.0 with two or four lanes. We'll eventually see single-lane SSDs in low-cost notebooks.
These products do not use DEVSLP for the lowest power states. Instead, PCI-SIG developed a low power state called L1.2. Like DEVSLP in SATA storage devices, not every manufacturer dedicates resources to enabling the feature. We’ve seen some devices come to market without L1.2 but later gain the feature through a firmware update.
Unlike SATA, NVMe storage controllers can operate over custom drivers that add hidden functionality. The Microsoft driver built into Windows 8+ is a narrow range driver that provides the basic instruction set needed for all devices to work. Custom drivers let manufacturers add features through commands to the device. Every custom drive we’ve tested has reduced read latency, an area closely tied to the user experience. Every custom drive we’ve tested also reduces notebook battery life.
Notebook Battery Life
There is a 142 minute gap between the best and worst result in the NVMe SSD category. The Samsung SM951 series is an OEM model, and we’re not surprised to see it at the top of the chart. We used the Microsoft driver on the SM951 SSDs.
Peppered throughout the results you will see drives with a driver designation—either MS for Microsoft or a company name for the custom driver. The custom driver results are often found in the bottom half and the Microsoft driver test with the same product in the upper half.
Power Restricted Performance
The performance under reduced bus speed shows where all of the power goes when you load the custom driver. There is a very large gap, just as we saw in the previous chart, between the same devices running with and without the driver. We are most likely seeing a longer delay between the changes in power states.
There are several Phison PS5007-E7 devices in the top of the performance chart as well. It’s been reported that this controller doesn’t change power states, and in at least one firmware revision the power consumption actually increases when it should decrease.
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