The Samsung 980 SSD is Samsung's first attempt at establishing a foothold in the lucrative DRAM-less SSD market. On an SSD, the DRAM cache is used to buffer the mapping tables of the SSD, which keep track of where a certain piece of data is located. Basically, it translates between linear disk addresses (as seen by the operating system) and the actual location of the data—which NAND flash chip, at which address in that chip. Your files are not stored as a contiguous block of bytes in an SSD either. Rather, the parallel nature of multiple flash channels is utilized to spread the data over multiple channels/NAND dies to profit from parallelization—this is what achieves multi-Gigabyte transfer rates. While the DRAM cache is one of the cornerstones of SSD performance today, it is also a cost factor. Typically, you need 1 GB of DRAM per TB of SSD capacity, which adds a few dollars to the production cost. That's why DRAM-less drives can be more affordable.
While the Samsung 980 Pro uses a PCIe 4.0 "Elpis" controller, the Samsung 980 non-Pro is built around a PCIe Gen 3 "Pablo" controller. We've seen Pablo on a bunch of Samsung portable SSDs before, but never on an M.2 client SSD. The new controller is a 4-channel design that's clearly optimized for cost and seems engineered for DRAM-less operation. Why do I say that? Looking at our DRAM-less testing on Page 5, the results for the Samsung 980 are REALLY impressive. It basically is twice as fast as all competing DRAM-less designs, in some test configs even more than 10x (!) as fast as the 1st-gen DRAM-less Crucial BX500. To me, this doesn't look like a simple evolutionary improvement of the DRAM mapping table paradigm, but, rather, Samsung apparently solving the flash translation layer problem completely differently. They have countless patents for SSD technology, many of those related to mapping tables
. Of course, Samsung isn't telling anyone their secret sauce in the 980 SSD, so I doubt we'll ever know.
The bottom line is that the Samsung 980 is the fastest DRAM-less drive I ever tested. Looking at our real-life performance test suite, the drive is really acing these benchmarks. These are not simple synthetic tests you can easily optimize for. We're running the actual application, on a drive that's 80% full, so the SLC cache is properly stressed, too, like it would be in real-life situations. Averaged over all tests, the Samsung 980 Pro is faster than any other PCIe 3.0 drive with the exception of the Hynix Gold P31, which is 1% faster. Famous drives with DRAM can barely keep up with the Samsung 980, with the ADATA SX8200 Pro performing the same, Kingston KC2000 1% slower, HP EX950 2% slower, and Crucial P5 4% behind. Compared to the Samsung 970 EVO, the performance uplift is 7%—I'm impressed since this is much better than I expected. Compared to the Samsung 980 Pro PCIe 4.0 flagship, the difference is only 4%. The fastest SSD we ever tested, the WD Black SN850, is only 5% faster. Remember, these are averages. I'm sure there are scenarios where you can make the DRAM-less design choke on incoming data, and for highly sequential workloads the PCIe 4.0 drives will of course be faster. Still, given the workloads we're testing in our review, I wouldn't be able to tell that this is a DRAM-less drive.
Sequential write performance of the Samsung 980 is fine for nearly all consumer workloads. With 158 GB, the pseudo-SLC cache is large and should be able to soak up all but the largest workloads. Where the 980 falls behind a bit is in how fast it can fill its whole capacity. With 593 MB/s, this is definitely on the low side, especially compared to high-end PCIe 3.0 SSDs, which achieve around 1 GB/s here. Once again, we're testing our real-life benchmarks at 80% disk full, so the SLC cache size is accounted for in our real-life performance results, which are impressive. Of course, momentarily stopping the write activity will have the SLC cache free up capacity immediately, so full write rates are available as soon as you give the drive a moment to settle down.
Unlike some other high-end M.2 NVMe SSDs, the Samsung 980 does not come with a heatsink preinstalled, and it doesn't need one. Even our worst-case thermal loading test left the SSD without a hint of thermal throttling—very impressive. This clearly sets the drive apart from Phison and SMI-powered drives, which do run into thermal throttling in some situations. The magic lies in the controller, which must be a very energy-efficient design—lower energy consumption means less heat output, which avoids throttling.
Currently, the Samsung 980 1 TB SSD retails for $140, which is quite a lot. Let's be real here. This is a DRAM-less SSD that consists of a controller and just one flash chip—such designs usually cost around $100 or below. Samsung is simply slapping their "Samsung tax" on it and hoping people will happily buy into that. At that price point, there are PLENTY of alternatives to the 980 SSD. For example, we recently reviewed the Hynix Gold P31, which is the fastest PCIe 3.0 SSD we ever tested: $135. The ADATA SX8200 Pro is $130, Kingston KC2500 is $135, and HP EX950 is $140. All these SSDs have DRAM and higher sustained write speeds, so they'll be able to handle corner cases better than the Samsung 980. If, however, Samsung sees the light and decides to position the 980 SSD at around $110–$120, they could kill the whole DRAM-less value SSD market. Drives like the ADATA Swordfish, or even the Crucial P1, would be pushed out of the market, and if Samsung can keep volumes up, they can establish themselves as the price/performance client SSD market leader.