For most gaming PCs, the Samsung 990 Pro and the WD Black SN850X are close enough that the better pick is whichever one is available in your capacity, with the right heatsink option, from a seller offering a solid warranty. Both are PCIe 4.0 x4 NVMe drives aimed at gamers, both use TLC flash, and in real game loading the gap between them is usually too small to notice. The differences show up in efficiency, software, capacity options and a few workload edge cases.
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What Each Drive Is
The Samsung 990 Pro is Samsung’s high-end PCIe 4.0 M.2 2280 drive. The maker lists sequential speeds of up to roughly 7,450 MB/s for reads and 6,900 MB/s for writes on its larger capacities, and sells it in several capacity tiers, with and without a factory heatsink. Samsung pairs it with its own Magician software for health monitoring and firmware updates.
The WD Black SN850X is the long-running flagship of the WD_BLACK gaming line (the brand is now handled under the Sandisk name following the split from Western Digital’s other businesses). The maker lists sequential reads of up to about 7,300 MB/s and writes of up to about 6,600 MB/s on its faster capacities. It is available with or without a heatsink, including a PlayStation 5 oriented heatsink version, and it includes a Game Mode feature in its companion software, now branded Sandisk or WD_BLACK Dashboard depending on the release.
Both are PCIe 4.0 drives. Neither saturates PCIe 5.0 bandwidth, so they are not competing with PCIe 5.0 drives such as those built on the Phison E26 controller. If you have a PCIe 5.0 M.2 slot, these drives will still work, they just run at 4.0 speed.
Key Differences at a Glance
| Area | Samsung 990 Pro | WD Black SN850X |
|---|---|---|
| Interface | PCIe 4.0 x4, NVMe | PCIe 4.0 x4, NVMe |
| Form factor | M.2 2280 | M.2 2280 |
| Maker-listed peak sequential read | Around 7,450 MB/s | Around 7,300 MB/s |
| Maker-listed peak sequential write | Around 6,900 MB/s | Around 6,600 MB/s |
| Flash type | TLC | TLC |
| Heatsink variants | Yes | Yes, including a console-focused version |
| Capacity range | Roughly 1 TB to 4 TB | Roughly 1 TB to 4 TB (a smaller option has also been sold) |
| Software | Samsung Magician | WD_BLACK or Sandisk Dashboard with Game Mode |
| Power behavior | Reviewers generally describe it as efficient | Reviewers generally describe it as efficient in recent revisions |
Exact numbers vary by capacity and by firmware revision, so read the datasheet for the specific size you are considering. The smallest capacity of most NVMe lines is typically a little slower on writes than the larger ones.
Gaming Performance in Practice
Game load times depend on much more than raw sequential speed. Asset decompression, CPU speed, shader compilation and the game engine itself dominate. Reviewers who compare PCIe 3.0, 4.0 and 5.0 drives in games commonly report differences of only a second or two in typical loading scenarios, and the 990 Pro and SN850X sit in the same tier. DirectStorage titles can benefit more from fast random reads and low latency, yet even there both drives sit near the top of the PCIe 4.0 class.
Random read performance at low queue depth is the number that matters most for everyday feel, and both drives are strong there. If a review shows one drive winning by a small margin in a synthetic test, treat it as a tiebreaker, not a reason to pay noticeably more or to wait for stock.
Where They Actually Differ
Thermals and heatsinks
Fast NVMe drives throttle when they get hot. Many motherboards ship with M.2 heatsinks or shields, and these are usually enough for a PCIe 4.0 drive. A drive-mounted heatsink matters mainly if your motherboard has no shield, if the slot sits directly under a hot graphics card, or if you are putting the drive in a console. Check clearance before buying a heatsink version, since a tall heatsink may not fit under a long GPU backplate or a motherboard cover. Do not stack a drive heatsink under a motherboard shield unless the board maker explicitly allows it.
Efficiency and laptops or handhelds
Reviewers have noted that the efficiency of each drive changes across firmware and controller revisions. If you are building a compact or mobile system, look for a recent review of the exact revision you will receive, since power draw and idle behavior are the usual differentiators there.
Software
Samsung Magician offers health reporting, firmware updates and optional features such as over-provisioning controls. The WD_BLACK or Sandisk dashboard offers health reporting, firmware updates and a Game Mode toggle. Game Mode is a maker feature that adjusts background behavior; treat it as optional, and read the maker’s description before enabling it, since its effect depends on the drive and firmware.
Endurance and warranty
The maker typically lists endurance in terabytes written, with the 1 TB and 2 TB models listed in the several-hundred to over-a-thousand TBW range, and warranties of around five years. Look at the exact endurance rating and warranty terms on each maker’s product page for your capacity. For gaming use, you are very unlikely to approach the rated endurance of either drive within the warranty period.
Who Should Pick Which
Gaming builders
Either drive is a sound main game drive. Pick the one that is available in your capacity and has the heatsink arrangement you need. If you are buying a 2 TB or larger drive, the extra capacity matters far more than the brand, because modern game libraries grow quickly.
Creators and heavy file movers
If you move large video files or work with big project folders, sustained write behavior matters. Both drives use pseudo-SLC caching, which means writes are fast until the cache fills and then drop to a slower rate. Larger capacities have bigger caches and hold speed longer. Creators who regularly write hundreds of gigabytes at a time should favor larger capacities from either maker and consider a separate scratch drive.
Budget-minded buyers
If budget is the constraint, a good PCIe 4.0 drive with a smaller price premium over a mainstream drive is usually the smarter buy than chasing the highest listed speed. Look at the next tier of drives as well; many mainstream PCIe 4.0 drives deliver very similar game loading results to these two.
Console owners
For a PlayStation 5, the maker-supplied heatsink variants of drives like the SN850X are designed with the console’s M.2 bay in mind, and Sony publishes its own requirements for compatible drives. Confirm the heatsink height and the drive specification against Sony’s published guidance before buying.
Common Myths
- Higher MB/s always means faster games. Game loading is bottlenecked by other things, so small sequential differences rarely change what you feel.
- You must buy PCIe 5.0 for a modern build. Reviewers consistently report little gaming benefit from PCIe 5.0 drives today, with higher heat and cost.
- A heatsink is mandatory. Many boards already include one. A drive heatsink helps when there is no shield or airflow is poor.
- Drives wear out quickly from gaming. Games mostly read data. Endurance ratings are far above typical gaming write volume.
Practical Recommendation
Choose by availability, capacity and warranty rather than the headline speed. Prioritize a 2 TB drive if your library is large, confirm your motherboard slot supports PCIe 4.0 x4 at full speed, and check whether a heatsink is already included on the board. Keep firmware updated through the maker’s tool, and keep a backup of anything important, since no SSD is a substitute for backups.
Frequently Asked Questions
Is the 990 Pro faster than the SN850X?
On paper the 990 Pro lists slightly higher peak sequential speeds. In games and everyday use the difference is typically too small to notice. Random performance and sustained write behavior depend on capacity and firmware.
Do I need the heatsink version?
Not if your motherboard already has an M.2 heatsink over the slot. If your slot has no cooling, or if you are installing in a console, a heatsink version is a sensible choice. Check the clearance first.
Will these drives work in a PCIe 5.0 slot?
Yes. PCIe is backward compatible, so the drives run at PCIe 4.0 speed in a 5.0 slot. You will not gain speed, but you will not lose compatibility either.
Can I use either drive in a PlayStation 5?
Both are PCIe 4.0 M.2 2280 drives, which matches the console’s general requirements, but you should check Sony’s published guidance on speed, size and heatsink height. The console-specific heatsink versions are the simplest option.
Which drive lasts longer?
Both makers list comparable endurance ratings at the same capacity, and both offer multi-year warranties. In normal gaming use, neither is likely to reach its rated limit. Look up the exact TBW and warranty period for your capacity on each product page.
Should I wait for a PCIe 5.0 drive instead?
For gaming, reviewers report little real-world benefit from PCIe 5.0 today. PCIe 5.0 drives also tend to run hotter. Unless you have a specific heavy file-transfer workload, a PCIe 4.0 drive like these is a practical choice.
