Samsung prints 7,450 MB/s read and 6,900 MB/s write on the 990 PRO 2TB page, and independent tests agree with those numbers. They also describe a burst, and most of what I want to say about this drive concerns the minutes after the burst ends.
Lab data for this drive is plentiful. Detailed long-term owner reports on the 2TB model are much rarer, so I will mark which is which.
Product image from the Amazon listing.
Fast Until the Cache Fills
KitGuru measured about 7,480 MB/s read and 6,880 MB/s write, right on Samsung’s claim. Those numbers come from data landing in a fast cache. The drive treats part of its flash as quicker SLC memory, and KitGuru describes a region that can grow to 226GB on the 2TB model.
Related reading
Other testers put the size in the same area. SSD-Tester wrote a single 300GB file and found the cache full after about 230GB. Across the whole file, the drive averaged 2,968 MB/s for writes and 6,107 MB/s for reads. ComputerBase saw the cache run out at roughly 250GB, with writes after that staying at 1,500 MB/s or better.
So the real shape is this: a fast run for the first 230GB or so, then a much slower plateau. Some rough arithmetic shows what it means. Copying 1TB in one go puts about 770GB in the slower phase, and at 1,500 MB/s that part takes more than eight minutes. It is still quick by any normal standard. An external hard disk would need hours. But the 6,900 figure does not describe that job, and ComputerBase noted that the WD Black SN850X stays in its fast mode longer and gives steadier results.
Who feels this? Video editors dumping a full card, people moving a whole photo archive, anyone cloning one drive to another. Most daily work never writes 230GB at once, and the cache refills when the drive is idle.
Product image from the Amazon listing.
Check the Firmware Before Anything Else
This is the one thing every buyer must do. Early drives had a real fault. Owners saw the health reading fall far too fast, and Samsung released firmware 1B2QJXD7 on 13 February 2023. An Ars Technica report explained the catch: “it doesn’t reset the wear percentage counter.” The fix stops the counter from racing ahead, and damage already recorded stays on the books.
The Level1Techs thread from that week gives a clear owner example. One 2TB owner had written 4TB and saw 4 percent of life used, a level the poster said should arrive only after 48TB. That matches the drive’s 1,200TB rating on SSD-Tester: 4 percent of 1,200TB is 48TB. After the update, the reading stayed at 4 percent, and the owner hoped it would simply sit there for a long while. A second owner also reported that nothing changed after updating and planned to watch the drive and return it if wear kept climbing.
NAS Compares lists the 2TB model among the affected drives, with 1B2QJXD7 as the fix. Drives made after the fix should be fine, but I would not assume. On day one, read the firmware version and the percentage used. A nearly unused drive should read close to zero.
This may create a real problem for Mac owners, and it is the part of this review I would underline. Samsung’s Magician software is the usual way to update. Some Mac users on MacRumors report that the macOS version of Magician shows the firmware number but does not offer to update the drive. Please take that as a warning to check rather than a settled fact. My own advice is simple: if you have any access to a Windows PC, update the drive there before it goes into a Mac enclosure.
Related reading
Product image from the Amazon listing.
Heat Is Mostly a Non-Issue, With One Exception
The bare drive is less of a heat problem than its reputation suggests. In its review, CDRLabs recorded around 37 °C at idle and up to 69 °C under heavy load, with no effect on speed.
ComputerBase pushed harder. During sustained full-drive writing with no cooler, the 2TB reached up to 82 °C, and the drive survived by lowering its speed. Samsung’s own heatsink version cut that by only 6 °C in their comparison, which used a 1TB unit, and the gap shrank as the load went on. A heatsink from an Asus motherboard held a 2TB drive to 69 °C. ComputerBase’s view was that Samsung’s heatsink mostly absorbs short peaks.
If your motherboard has an M.2 cover, use it. Do not pay much extra for Samsung’s heatsink version on that evidence.
The exception is a small closed box, which brings me to the question many readers here will have.
In an External Box, Pick the Box First
Plenty of people buy this drive for an external enclosure, and I think many of them overspend. The enclosure decides the speed.
A 10 Gbps USB link is about 1.25 GB/s on paper, before overhead. That is below the 1,500 MB/s this drive holds even after its cache runs out. So in a 10 Gbps box, you would never see the slowdown, and you would also never see the speed you paid for. A cheaper drive would feel the same. Only a Thunderbolt or USB4 enclosure gives this drive room to matter, and even then the link will cap it well below the numbers on Samsung’s page.
Owner reports on enclosures are scattered, and they are about the whole setup more than the drive. One useful case is an Apple forum thread. A Mac mini M2 owner’s WD SN850X kept dropping out of an Acasis TBU405 Thunderbolt enclosure during Time Machine backups, even with a fan pointed at it, so heat was ruled out. Swapping to a 990 Pro in the same enclosure, the owner reported it “works like a charm”: a first backup of about 1.26TB finished, and the following week passed with no disconnects. That drive was the 4TB model, not this one.
Another Mac report points the opposite way, with one MacRumors owner of a 990 Pro in an OWC enclosure reporting frequent unsafe shutdowns when the Mac sleeps. That fits a pattern: sleep settings and enclosure chips seem to cause as much trouble as the drive does.
Related reading
Two gaps should be clear. I found no owner who measured a long write inside an enclosure with this exact 2TB drive, and I found no report on restoring a large backup from one. If the drive holds your only backup, test a restore yourself.
A Fine Internal Drive, an Expensive External One
For an internal slot in a PC with a PCIe 4.0 connection, I like this drive. CDRLabs listed the 5-year warranty among its highs, SSD-Tester gives the same term with DRAM on board, and the lab results are consistent. Buy it if you work with big files and want quick bursts, and if you are willing to check the firmware on the first day.
Skip it if you plan to write hundreds of gigabytes at a steady rate all day, since drives that hold their fast mode longer exist. Skip it as well if it is headed for a 10 Gbps USB enclosure, because you would pay for speed the box throws away. Mac owners with no PC nearby should think twice, as firmware updates may be hard for them.
If an internal PC build is your plan, the Samsung 990 PRO NVMe SSD 2TB is a solid pick, provided the firmware reads 1B2QJXD7 or later when it arrives. This is an affiliate link. As an Amazon Associate I earn from qualifying purchases.
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