250GB Samsung 840 Series 2.5" SATA Internal Solid State Drive (SSD) w/ Notebook/Desktop Installation Kit (MZ-7TD250KW) $150 + Free Shipping

At least in MLC flash, the move to 3Xnm halved the P/E cycles so we would be looking at 1250 cycles. 2Xnm brought even fewer cycles, roughly 3,000, and with same math we get 750 cycles for 2Xnm TLC.

we can also note the very low write speeds for the TLC-equipped Samsung 840.

The voltages we recorded with the Samsung 840 are higher than the Samsung 840 Pro across the board, and also exhibit one of the highest idle voltages that we have witnessed. This is probably due to some hefty background processes to handle the TLC NAND. The only area where the Samsung 840 performed admirably was in the Startup voltage, which came in at a very low 1.13W.

The random write voltage was unsurprisingly very high, and the sequential write voltage requirement is also on the high end. With this being a relatively new SSD, with its TLC destined to begin producing more errors over the life of the drive, we would expect these power consumption figures to grow over the life of the SSD. Even with these relatively 'fresh' readings we feel that this would not be the best SSD for mobile applications.

The low write speed offered with the Samsung 840 Series is going to be a concern for some users. It is especially important that users with moderate to heavy write workloads carefully weigh other options before making the jump to a TLC SSD. The low write speed will be an immediate problem in large file transfer situations, and endurance will be a long-term problem. It is also important to note that the 120GB model of this SSD only has a sequential write speed of 130MB/s and random read IOPS of 32,000, significantly lower than the lackluster write performance that we observed today in our testing.

Including a thermal pad for the controller would help to keep the device cool. We would like to see thermal pads with this SSD when we take the higher power consumption figures from TLC NAND into consideration.

Our steady state testing essentially places a workload upon the SSD until it is forced to begin running the internal management routines and garbage collection during actual usage. This is especially important with this type of NAND as it is definitely going to experience far more data errors than MLC over time. This will create increasing overhead for the MDX controller over the lifetime of the device. The read speed degradation that we observed is worrisome due to the fact that the increasing error rates can trigger these drive management routines, in effect creating read speed degradation in lower usage scenarios than with MLC NAND.

The extreme loss of write performance in steady state in our Iometer testing can also be a sign of long term performance issues in steady state as the NAND ages.