Did you notice the missing Notebook Battery Life tests that we normally run on client SSDs? This brings us to a sour note when dealing with NVMe: compatibility. Even though our Lenovo X1 Carbon Gen 3 fully supports the AHCI-attached SM951, the NVMe model will not boot in the Broadwell-based platform. Lenovo may add support at a later date, but as of right now, the system kicks out an error telling us that it can't start up. Without boot support, we can't run our barrage of battery life tests on the SM951-NVMe.
And this points to an even larger problem. Several motherboard manufacturers released NVMe-enabled firmware updates for new X99 and Z97 platforms. But older boards haven't received the same love. Many users upgrading to cutting-edge storage products are building them into completely new configurations. There is an even larger group of enthusiasts with older Z87- and Z77-based machines, though. If your board vendor of choice isn't deliberately adding NVMe support, you won't be booting to an NVMe drive any time soon. We hope this will happen over time, but we aren't holding our breath that years-old motherboards will suddenly get new features.
If you already purchased a Samsung SM951 SSD with AHCI, then we can't recommend the NVMe model for its slight performance boost. It's faster, but only slightly. Moving from an 850 Pro to the SM951-NVMe is a nice upgrade though, and you will notice snappier performance from the reduced latency.
Compatibility obviously needs to be considered, but we also feel capacity should be included in your purchasing decision. The SM951s are limited to a maximum capacity of 512GB, while Samsung's 850 Pro scales to 1TB. That could be a problem for you if your Steam/Origin folder is bursting at the seams.
The 850 Pro 256GB is one of the fastest SATA-based products on the market today. Samsung's SM951-NVMe 256GB is the fastest client PCIe drive smaller than 400GB. We expect it to sell for just over $256 when it's released. That's much less than Intel's SSD 750 400GB NVMe SSD. If you want performance beyond what SATA offers but don't want to spend big money on unused capacity, the smaller SM951-NVMes are a good choice.
When they become available, we'll published performance results from the SM951-NVMe 128GB and 512GB models. We're excited to see how the SM951-NVMe 512GB compares to Intel's SSD 750 400GB.