Many people are buzzing about the Samsung 840 Pro, but we think the drive has a split personality. This is an approach several companies are actively working on and we'll see more of it in 2013. OCZ's Vertex 4 and Vector do the something similar with performance and storage mode and Samsung does it behind the scenes without giving the behavior a name. We have a new drive in from Toshiba and a couple of drives under NDA till January 7 (CES), all with high performance initially and a fall back mode. The Samsung approach is quite a bit different from these other drives, but the end results are the same.
When the Samsung 840 Pro starts working the data in the background the write performance suffers with lower write speeds and increased latency. This is common with most SSDs, but only when the drive runs out of clean flash. The normal methods are to wait until the drive is idle and then perform the background clean up tasks, the 840 Pro doesn't wait for idle time - it just gets to work right away. If you do a lot of disk intensive tasks then you'll feel a loss of performance.
The good news is performance comes back and fairly quickly. The image above is a test after 30 to 40 minutes of idle time. The Samsung 840 Pro went through the clean up cycle and all of the write performance returned. The 840 Pro 256GB didn't seem to go into clean up mode as quickly as the 128GB we looked at today. We'll take a look at that drive in a few days.
So the real question everyone wants answered is what drive to buy, the OCZ Vector 128GB or the Samsung 840 Pro. These are the two big powerhouse drives in this capacity size with the SuperSSpeed S301 SLC kind of off to the side as an alternative, expensive option. To answer that question you need to figure out how you use your computer. If you write a lot of data to your drive rapidly, the Samsung option will shuffle that data and your user experience will decrease due to the additional latency. The Vector on the other hand will switch to storage mode and the sequential performance will decrease for a short time. Personally, I can live with slower sequential reads and writes when working on my PC, but increased latency is a deal breaker since it slows everything else down that I'm trying to accomplish. The OCZ drive has a built-in multitask safeguard which limits QD1 reads so you have additional bandwidth for another task, that's why we don't see storage mode increasing latency in AIDA64.
Other drives also just on the outskirts of top performance are also an option. Drives like the Plextor M5 Pro and Corsair Neutron GTX don't have the bipolar personality 'feature', at least not to the same degree as Vector and 840 Pro. Shopping for a 128GB SSD is difficult now since nothing really stands out as the ultimate everything to all drive.
In this capacity size, I think Vector is a better option, but it's pretty close. The power test really pushes Vector to the top of the list since it offers better battery life over 840 Pro. Then again, if you are exclusively worried about battery life there are drives on the market that offer much longer battery life over Vector. We have a LSI SandForce drive in the lab now with new B02 silicon and it offers longer battery life than anything else we've tested.