Where they actually differ
The most decisive specs, ranked by how much they matter — before the full spec table.
| Spec | Samsung - 990 PRO 2TB | WD - Black SN850X 2TB |
|---|---|---|
| Sequential write | 6900 MB/s | 6600 MB/s |
| Sequential read | 7450 MB/s | 7300 MB/s |
Between the 990 PRO 2TB and Black SN850X 2TB, the 990 PRO 2TB comes out ahead in sequential write / sequential read, while the Black SN850X 2TB wins on several specs. Overall, the 990 PRO 2TB scores 69.2 and the Black SN850X 2TB scores 68.7 on our Mars Score.
Which should you buy?
These two are nearly even on the Mars Score (69.2 vs 68.7). The decision is not about overall quality — both clear the bar — it is about which specific trade-offs fit your use.
Pick the 990 PRO 2TB if you care most about sequential write / sequential read. The biggest gaps in its favor are sequential write, sequential read. The single most decisive one: Sequential write — 4.55% more. 6900 MB/s vs 6600 MB/s.
The Black SN850X 2TB similarly does not carry a headline advantage on the popular specs — look at the full table for category-specific deltas.
Both ship with comparable capacity, interface, endurance (tbw), so those specs do not separate the two — focus on the differences below.
Bottom line: there is no wrong answer here — match the spec advantages to how you actually use the product. The Mars Score parity says both are well-rounded; the differences are about trade-offs, not quality.
Which should you buy: Samsung - 990 PRO 2TB or WD - Black SN850X 2TB?
Samsung - 990 PRO 2TB leads the current Mars Score by 0.5 points.The more useful decision is the trade-off behind that result: compare sequential read, sequential write against the way you will actually use the product.
Choose Samsung - 990 PRO 2TB if…
Samsung - 990 PRO 2TB has the measurable edge on write mbps, read mbps.
Choose WD - Black SN850X 2TB if…
WD - Black SN850X 2TB does not lead a decisive measured field here, so choose it for price, ecosystem, design, or availability when those matter more to you.
This is a structured comparison of the published catalog values. It is not a claim of identical real-world performance across every workload; use the linked spec drill-downs and methodology page to inspect the inputs.
Why Samsung - 990 PRO 2TB wins
- ▲Sequential write — 4.55% more. 6900 MB/s vs 6600 MB/s.
- ▲Sequential read — 2.05% more. 7450 MB/s vs 7300 MB/s.
Why WD - Black SN850X 2TB wins
- No decisive advantages.
Spec comparison
Capacity
| Spec | Samsung - 990 PRO 2TB | WD - Black SN850X 2TB |
|---|---|---|
| Capacity | 2000 GB | 2000 GB |
Performance
| Spec | Samsung - 990 PRO 2TB | WD - Black SN850X 2TB |
|---|---|---|
| Sequential read | 7450 MB/slead | 7300 MB/s |
| Sequential write | 6900 MB/slead | 6600 MB/s |
| Interface | PCIe 4.0 x4 | PCIe 4.0 x4 |
| Form factor | M.2 2280 | M.2 2280 |
Endurance
| Spec | Samsung - 990 PRO 2TB | WD - Black SN850X 2TB |
|---|---|---|
| Endurance (TBW)ⓘ | 1200 | 1200 |
| Warranty | 5 yrs | 5 yrs |