Lexar NM790 4TB SSD with Heatsink Review: Gen4 NVMe Done Right

Speed numbers are easy to print on a box. What they don't tell you is what happens when that box is actually doing something useful, like writing a 50GB game update, ingesting raw video, or just being your daily driver for the next five years. The real questions are: what's the controller, what's the NAND, is there DRAM on board, and what does the endurance rating tell you about how much faith the manufacturer actually has in its own product? Get those answers right and the rest mostly falls into place.

The Lexar NM790 4TB SSD with Heatsink gets those answers right. This is a proper Gen4 NVMe drive with TLC NAND, a DRAM cache, a controller that published benchmarks have consistently praised, and a 4TB capacity that costs a fraction of what that used to. The 4.7-star average across over 2,000 owner reviews isn't a fluke either. This drive is genuinely good. But it's not perfect for everyone, and there are a couple of things worth understanding before you click buy, so let's get into the detail.

The verdict up front: if you want a big, fast, reliable Gen4 NVMe drive for a PS5, a gaming PC, or a creative workstation, the NM790 4TB is one of the most sensible buys at this capacity right now. It's not the absolute cheapest per gigabyte, but it's not trying to be. It's trying to be good. And it mostly succeeds.

The NAND is 3D TLC, which matters a lot. TLC means three bits per cell, which is the sensible middle ground between the lightning-fast-but-expensive SLC/MLC and the cheap-but-compromised QLC. TLC is what the best mainstream drives use, and it's what you want. The controller is the Maxio MAP1602, which has been independently benchmarked by the storage community and shown to be a genuinely capable chip, not a budget afterthought. Crucially, the NM790 has an on-board DRAM cache, which means it's not leaning on your system's RAM via Host Memory Buffer to manage its mapping tables. That matters for sustained workloads and random I/O consistency.

Random read performance is rated at 1,000,000 IOPS and random write at 1,400,000 IOPS. Those are the numbers that actually determine how fast your system feels day to day, far more than the sequential figures. The rated endurance is 3,000 TBW (terabytes written) for the 4TB model, and the warranty is five years. Both of those numbers are telling you something important, which we'll get into properly in the endurance section.

The M.2 2280 form factor is the universal standard. It's 22mm wide and 80mm long, and it slots into the M.2 slot on virtually every desktop motherboard made in the last five years, most modern laptops, and the PS5's expansion bay. The NM790 specifically lists PS5 compatibility, which is relevant because Sony requires a heatsink for the M.2 expansion slot, and this drive comes with one already attached. That's a genuine convenience, not just a box-ticking exercise.

One thing worth being clear about: if you're running a Gen3 motherboard, this drive will work, but it'll run at Gen3 speeds (roughly 3,500MB/s sequential read). You won't get the full 7,400MB/s. That's fine for most uses, the drive will still feel fast, but if you're in a Gen3 system and you're buying this specifically for the Gen4 speed, you might want to reconsider. For everyone else on a modern platform, you're getting the full spec.

Owner reports across the 0 back this up in practical terms. People consistently describe fast boot times, snappy application launches, and game load times that are genuinely quick rather than just "not terrible". The kind of feedback you see from owners who've been using drives for months and notice the difference when they go back to something slower. One pattern that comes up repeatedly is that owners who installed this as a PS5 expansion drive report load times that are competitive with the PS5's internal SSD, which is a meaningful benchmark given how fast Sony's internal storage is.

For large sequential transfers, copying a 100GB folder or writing a big video project, the sequential write speed of 6,500MB/s is excellent in burst mode. Whether that speed holds after the SLC cache fills is a separate and important question, which we'll address in the next section. But for the kind of mixed workloads most people run (booting, gaming, browsing, the occasional big file copy), the NM790 performs like a proper enthusiast drive, not a budget unit wearing a fast label.

For the NM790 at 4TB, the SLC cache is proportionally large because there's a lot of NAND to allocate from. Published benchmarks for the NM790 show that the cache is substantial enough to handle most real-world workloads without exhaustion. Typical consumer tasks, installing games, copying a few big files, writing a video export, rarely push through the full cache. But if you're doing sustained sequential writes of genuinely large datasets, think writing hundreds of gigabytes continuously, you will eventually hit native TLC speeds. The good news is that TLC native write speed is meaningfully better than QLC native write speed, which can drop to genuinely painful levels (sometimes under 200MB/s on cheaper QLC drives). TLC holds up better after cache exhaustion.

The DRAM cache also helps here. A drive without DRAM has to use your system's RAM (via Host Memory Buffer) to manage its mapping tables, and under sustained load that can introduce latency spikes and inconsistency. The NM790's on-board DRAM means the drive manages its own mapping independently, which keeps random I/O consistent even under sustained pressure. This is one of the reasons the NM790 feels solid in extended workloads where a DRAM-less drive might start to feel stuttery. For creative professionals doing sustained disk-heavy work, that DRAM cache is not a luxury, it's a necessity.

The 3D TLC NAND is the other thing to feel good about. There's been a worrying trend of manufacturers quietly swapping TLC for QLC in drives that were originally launched with TLC, especially as NAND prices have fluctuated. Lexar specifies TLC for the NM790, and owner reports don't suggest any quiet NAND swap has happened at the 4TB capacity. QLC would be a problem here: QLC's native write speed is genuinely bad, its endurance per cell is lower, and it's typically sold as a cost-cutting measure dressed up as a capacity win. TLC is the right choice for a drive at this capacity and price point, and Lexar made it.

The on-board DRAM cache is the third pillar. DRAM-less drives are fine for a boot drive in a budget build. They're less fine as a 4TB workhorse that's going to be written to heavily and accessed constantly. The DRAM stores the drive's logical-to-physical mapping table, which is the index the controller uses to find data. Without DRAM, that table has to live somewhere else, either in the NAND itself (slow) or in your system RAM via HMB (dependent on your platform and the workload). With DRAM on board, the controller always has fast, consistent access to its own map. That's the difference between a drive that stays consistent under pressure and one that gets wobbly.

The five-year warranty is the other signal worth reading. Manufacturers who don't trust their own drives give you two or three years and hope for the best. Five years tells you Lexar is confident enough in the NM790's longevity to back it for the medium term. That's not a guarantee of immortality, drives can and do fail, but it's a meaningful commitment. And five years of warranty coverage means that if something does go wrong in the first half-decade, you're covered without an argument.

Owner reports across the 0 support this confidence. The 4.7-star average is high, and the failure pattern in the reviews is low. The negative reviews that do exist tend to cluster around dead-on-arrival units (which happens with any drive at volume, it's a manufacturing reality) rather than drives that failed after months of use. Long-term owners who've had the drive for six months or more consistently report it's running fine. That's the pattern you want to see: early failures handled under warranty, long-term reliability solid. Always back up your data regardless, no drive is a backup strategy on its own, but the NM790's track record is reassuring.

Published benchmark results for the NM790 show that with the heatsink in place, the drive maintains consistent performance through sustained workloads without significant throttling. Without a heatsink, Gen4 drives in a warm case or a PS5's enclosed bay can get warm enough to trigger thermal throttling, which is when the drive deliberately slows itself down to avoid overheating. That throttling shows up as a sudden drop in write speeds mid-transfer, exactly the kind of thing that makes a "fast" drive feel slow at the worst moment.

For PS5 users specifically, the heatsink is non-negotiable: Sony requires one for the M.2 expansion slot, and drives that ship without one require you to source your own. The NM790 solves that problem out of the box. For desktop users, if your motherboard has an M.2 heatsink or thermal pad, you might want to remove the drive's own heatsink to use the motherboard's solution instead, since most motherboard heatsinks are better integrated into the case airflow. But having the heatsink included means you're covered even if your board doesn't have one.

At current pricing, the NM790 4TB is competitive with other TLC Gen4 drives at this capacity. It's not the cheapest 4TB NVMe you can find, but the cheapest 4TB NVMe you can find is almost certainly QLC, and the endurance and sustained write performance difference between TLC and QLC at 4TB is significant enough to matter. If you're filling 4TB of drive with data you care about, you want TLC. The price premium over QLC alternatives is modest and worth it.

If 4TB is more than you need, the 2TB NM790 is a very sensible buy and costs meaningfully less. For most gamers, even those with large libraries, 2TB is enough if the drive is dedicated to games. But if you're using this as a single-drive solution for a PS5, a creative workstation, or a PC where you want everything in one place, 4TB is the capacity that actually solves the problem rather than just delaying it.

For PS5 installation, Sony has a clear guide on the process: power down the console, remove the expansion bay cover (it's under the side panel), slot the drive in at an angle, secure the screw, and replace the cover. The NM790's included heatsink means you don't need to source a separate one, and the M.2 2280 size is explicitly supported by the PS5. The PS5 will prompt you to format the drive on first boot, which takes a minute. After that, you can move games to and from the expansion drive directly in the console's storage settings.

For laptop users, check your laptop's M.2 slot specification before buying. Many laptops have M.2 slots but some are Gen3 only, some are SATA only (which won't work with an NVMe drive), and some have physical space limitations that mean a 2280 drive won't fit (in which case you need a 2242 or 2230). The NM790 is 2280, so if your laptop takes a 2280 NVMe, you're fine. If you're cloning an existing drive rather than doing a fresh install, tools like Macrium Reflect Free or the Lexar support page can point you toward migration options. Just make sure your target capacity is equal to or larger than your source drive's used space.

It's also a good fit for people who care about longevity. The 3,000 TBW endurance and five-year warranty make this a drive you can install and trust, not one you're watching nervously. If you've lost data to a failing drive before (and if you have, you know exactly how that feels), the NM790's endurance credentials are genuinely reassuring. Pair it with a backup strategy (an external drive, cloud storage, something) and you're in good shape.

Who should look elsewhere? If you genuinely only need 1TB or 2TB, the NM790 in those capacities costs less and still delivers the same controller and NAND quality. Don't buy 4TB of drive if you're going to leave 3TB of it empty for years. And if you're on a tight budget and just need a boot drive, there are cheaper Gen4 options that will do the job fine. The NM790 4TB is a premium-capacity purchase and the value case is strongest when you actually need the capacity.

The Samsung 990 Pro uses Samsung's own in-house controller and TLC NAND, and it's consistently one of the top performers in published benchmarks, particularly for random I/O. The WD Black SN850X uses a WD-designed controller and TLC NAND, and it's particularly strong in gaming-focused workloads (it's optimised for DirectStorage). Both have DRAM caches and five-year warranties. Both are genuinely great drives. But both cost noticeably more than the NM790, and in real-world use the performance gap between them is small enough that most users won't notice it.

The NM790 holds its own in sequential and random performance benchmarks, delivers TLC endurance and DRAM cache at a lower price, and comes with a heatsink. For most buyers, that's the better value proposition. The 990 Pro and SN850X are worth the premium if you're building a high-end workstation where you're genuinely pushing the drive hard every day and want Samsung's or WD's brand assurance. For gaming, PS5 expansion, and mixed creative workloads, the NM790 is the smarter spend.

One thing that table makes obvious: the NM790's 3,000 TBW endurance actually beats both the Samsung 990 Pro and the WD Black SN850X at 4TB, which both rate at 2,400 TBW. That's not a small difference. It's 25% more rated endurance, at a lower price, with a heatsink included. The 990 Pro's sequential write speed is slightly higher, and Samsung's brand carries weight, but the NM790 wins on endurance and value at this specific capacity. That's genuinely impressive.

The sustained write performance after SLC cache exhaustion is the one area where you should have realistic expectations. Like every consumer TLC drive, native write speed after the cache fills is lower than the headline number. But TLC native speed is far better than QLC native speed, and for most real-world workloads you'll rarely push through the full cache anyway. The DRAM cache keeps things consistent in mixed workloads. The thermals are managed by the included heatsink. The five-year warranty means you're covered if something does go wrong.

For PS5 users, this is one of the most sensible expansion drive purchases you can make right now. Large capacity, heatsink included, proper TLC NAND, strong random I/O, and a price that's fair for what you're getting. For PC gamers and creative professionals who want a big, reliable, fast Gen4 drive without paying Samsung tax, the NM790 4TB makes a very strong case for itself.

The honest don't-overspend line: if you don't actually need 4TB, the NM790 2TB is the smarter buy. Same controller, same NAND quality, same five-year warranty, significantly lower price. Buy the capacity you need, not the capacity that sounds impressive. But if you genuinely need 4TB of fast NVMe storage, the NM790 is the best value way to get it right now.

Score: 9 out of 10. Loses a point only because the NM790 brand doesn't yet have the decade-long reliability track record that Samsung or WD have built. The specs and owner reports are excellent, but time is the ultimate test for storage. Everything else about this drive is right.

No rating from 0 owner reviews.