Samsung's 870 QVO SSD was released earlier this month. It is one of the first consumer solid-state drives to offer capacities ranging up to 8 TB, which is important in achieving parity with mechanical HDDs. Internally, Samsung is using only in-house components, which no doubt helps keep manufacturing cost down. At the center of the 870 QVO is the new MKX controller, a refined version of the MJX that powered the 860 QVO. Next to it sits a single lonely QLC flash chip, which is built using Samsung's new V-NAND v5 process, with an impressive density of 8 Tb per chip. Last but not least, a DRAM cache chip is included to handle the mapping tables. This one's a modern LPDDR4 variant with 1 GB capacity.

If we look at our synthetic testing, the Samsung 870 QVO does very well. It achieves excellent results, especially when it comes to random and sequential writes. Random and sequential reads are a little bit lower than some competing drives, but the differences are small. If the review ended here, I'd definitely give the Samsung 870 QVO a recommendation, but well, it does not.

Our real-life test results paint a completely different picture of the SSD. Here, the 870 QVO can barely keep up. On average it is the second-slowest SSD we ever tested, only the aging Crucial BX500 is slower. Let's look at individual results. Game startup times are barely affected in absolute terms, maybe a second slower, not worth worrying about. In relative terms the 870 QVO is still trailing the pack. In apps, things are different. For example, in WinRAR extraction, which sends a huge amount of small writes to the SSD, the Samsung drive is the slowest by a huge margin. Surprisingly, even read-heavy scenarios are affected; "Text Search in Files" has the Samsung drive as the third-slowest. Another important data point is ISO file copy, which simply copies a large file and has this SSD trail 20% behind the second-slowest drive. Steam game decryption has you in-game three minutes later than your friends with NVMe. Performance results are also very unpredictable. We do ten runs of our real-life test suite, with a pause between each test and a reboot after every full run. The 870 QVO is the only drive in our test group that showed huge swings in the data, which means it will subjectively appear to suddenly slow down by a lot, and performance will recover only after a while.

The underlying reason for these results is the QLC technology in the 870 QVO. Writing to QLC NAND cells directly is slow, so all modern SSDs operate some of their capacity in single-cell SLC mode, which is much faster to write to. The SLC cache will soak up bursts of write activity, and the drive flushes data from SLC to QLC in the background when idle. Our "Write Intensive Usage" tests do exactly that, and the results are shocking. While the drive starts out great, at 500 MB/s, write rates drop fairly quickly, to below 100 MB/s, which is slower than most hard drives! Some people even have Internet faster than that. This could mean that when downloading from Steam or EGS, or copying files over the network, you'll be bottlenecked by the SSD, not by the connection. Samsung also chose a relative small SLC cache of only 42 GB, which is only a fraction of what we're typically seeing on QLC SSDs.

It almost looks as though the 870 QVO was engineered specifically to perform well in synthetic benchmarks to get decent review scores. This could also be useful for support cases of people wondering about the low performance, as "CrystalDiskMark is showing normal results, RMA denied". I also have to question the legality of "up to 530 MB/s". Yeah sure, "up to".. problem is the real number is 80% (!) lower than the claim. Maybe it's legal, but it's just wrong to mislead customers like that.

If the price is right, these performance numbers could still be justified. Some people might consider the 870 QVO as a large-capacity HDD replacement. The most affordable 1 TB SATA SSDs retail for around $90; our favorites, the Crucial MX500 and Seagate 120, are $115, and last-generation's Samsung 860 QVO is $110. That's probably why Samsung is asking $115 for the 870 QVO. That price is completely unrealistic because pretty much every other SSD you can buy will be faster than the 870 QVO. Most budget SSDs on the market use TLC flash, which operates much faster than the QLC on the 870 QVO. For $115 you can even find decent M.2 NVMe drives that are in a completely different realm performance-wise. Of course, not everybody has a PC with M.2 NVMe support, or your slots are already filled with other drives. I still can't recommend the 870 QVO for that scenario; rather, buy a decent TLC SSD, it'll perform better. If you feel you don't need a lot of performance and can wait a bit, sure, buy the cheapest SSD you can find, you'll save $30 and it will still perform better than the Samsung 870 QVO.