SanDisk Optimus GX 7100 1TB vs Western Digital WD_BLACK SN850X 1TB
SanDisk Optimus GX 7100 1TB and Western Digital WD_BLACK SN850X 1TB each win something the other does not — the choice is which of those you want.
| Specification | SanDiskOptimus GX 7100 1TB | Western DigitalWD_BLACK SN850X 1TB |
|---|---|---|
| Capacity (GB) | 1000 | 1000 |
| Sequential read (MB/s) | 7250 | 7300better |
| Sequential write (MB/s) | 6900better | 6300 |
| Current best price | $198.00at Amazon.com · captured 2026-09-13 | $189.62betterat Newegg · captured 2026-09-13 |
| Price per TB | $198.00 | $189.62better |
| Endurance (TBW) | 600 | 600 |
| Warranty (years) | 5 | 5 |
| DRAM cache | No | Yes |
| NAND type | tlc | tlc |
| Controller | — | Western Digital in-house 8-channel controller |
How these two compare
Sequential throughput
SanDisk Optimus GX 7100 1TB is rated 7250 MB/s read and 6900 MB/s write; Western Digital WD_BLACK SN850X 1TB, 7300 MB/s read and 6300 MB/s write. These are peak sequential rates over PCIe — the speed you would see copying one large file. For boot, app launches and everyday feel, random access matters more than this headline figure.
Random access
On random 4K access — the small, scattered reads and writes behind boot, app launches and general responsiveness — SanDisk Optimus GX 7100 1TB is rated 1,000,000 read and 1,400,000 write IOPS, Western Digital WD_BLACK SN850X 1TB 800,000 read and 1,100,000 write. This is the figure that follows everyday feel, where the sequential rates above follow big-file copies.
Price
SanDisk Optimus GX 7100 1TB lists at $198.00, or $198.00 per TB; Western Digital WD_BLACK SN850X 1TB at $189.62, or $189.62 per TB.
Endurance
The makers warrant 600 TBW on SanDisk Optimus GX 7100 1TB and 600 TBW on Western Digital WD_BLACK SN850X 1TB — how much writing each is rated to take before the endurance clause lapses. Most desktop workloads never come close, so read the two against each other rather than as a limit you are likely to reach.
DRAM cache
SanDisk Optimus GX 7100 1TB is DRAM-less; Western Digital WD_BLACK SN850X 1TB carries a DRAM cache. A DRAM cache holds the drive's mapping table — the index of where each block physically sits — so the controller places and finds data without an extra flash lookup. A DRAM-less drive borrows a little system memory (HMB) or a slice of its own flash instead, and is likelier to slow once a long run of random writes outlasts its fast cache.
NAND, controller and warranty
NAND: SanDisk Optimus GX 7100 1TB uses TLC and Western Digital WD_BLACK SN850X 1TB uses TLC. The tier is bits per cell — SLC, MLC, TLC and QLC from one to four — trading density against endurance and sustained-write speed: QLC is cheapest per gigabyte, TLC the mainstream balance, and the denser the cell the sooner sustained writes taper. On the controller: SanDisk Optimus GX 7100 1TB's controller is not stated, and Western Digital WD_BLACK SN850X 1TB uses the Western Digital in-house 8-channel controller. It is the chip handling error correction, wear-levelling and where each write lands — much of how a drive holds up under load — even if the part number on its own tells you little. On the cover: SanDisk Optimus GX 7100 1TB carries a 5-year warranty, Western Digital WD_BLACK SN850X 1TB carries a 5-year warranty. The length is the maker's own vote of confidence, and on an SSD it tends to track the endurance rating — a longer warranty usually meaning more rated writes.
Which to buy
There is no outright answer — each takes something the other gives up. Decide which of those advantages matters for your build; the comparison above lays out both sides.
Common questions about this pair
- Which is faster, SanDisk Optimus GX 7100 1TB or Western Digital WD_BLACK SN850X 1TB?
- SanDisk Optimus GX 7100 1TB is rated 7250 MB/s read and 6900 MB/s write; Western Digital WD_BLACK SN850X 1TB, 7300 MB/s read and 6300 MB/s write. These are peak sequential rates over PCIe — the speed you would see copying one large file. For boot, app launches and everyday feel, random access matters more than this headline figure.
- How do SanDisk Optimus GX 7100 1TB and Western Digital WD_BLACK SN850X 1TB compare on random access?
- On random 4K access — the small, scattered reads and writes behind boot, app launches and general responsiveness — SanDisk Optimus GX 7100 1TB is rated 1,000,000 read and 1,400,000 write IOPS, Western Digital WD_BLACK SN850X 1TB 800,000 read and 1,100,000 write. This is the figure that follows everyday feel, where the sequential rates above follow big-file copies.
- Which costs less per terabyte, SanDisk Optimus GX 7100 1TB or Western Digital WD_BLACK SN850X 1TB?
- SanDisk Optimus GX 7100 1TB lists at $198.00, or $198.00 per TB; Western Digital WD_BLACK SN850X 1TB at $189.62, or $189.62 per TB.
- Should you buy SanDisk Optimus GX 7100 1TB or Western Digital WD_BLACK SN850X 1TB?
- There is no outright answer — each takes something the other gives up. Decide which of those advantages matters for your build; the comparison above lays out both sides.