SanDisk Optimus GX 7100 500GB vs Western Digital WD_BLACK SN7100 500GB
SanDisk Optimus GX 7100 500GB is at least the equal of the other on every measure that decides this, and ahead on at least one.
| Specification | SanDiskOptimus GX 7100 500GB | Western DigitalWD_BLACK SN7100 500GB |
|---|---|---|
| Capacity (GB) | 500 | 500 |
| Sequential read (MB/s) | 6800 | 6800 |
| Sequential write (MB/s) | 5800 | 5800 |
| Current best price | £89.99betterat Amazon.co.uk · captured 2026-09-13 | £106.99at Amazon.co.uk · captured 2026-09-13 |
| Price per TB | £179.98better | £213.98 |
| Endurance (TBW) | 300 | 300 |
| Warranty (years) | 5 | 5 |
| DRAM cache | No | No |
| NAND type | tlc | tlc |
| Controller | — | WD/SanDisk in-house Polaris 3 (4-channel, DRAM-less) |
How these two compare
Sequential throughput
SanDisk Optimus GX 7100 500GB states 6800 MB/s read and 5800 MB/s write; Western Digital WD_BLACK SN7100 500GB states 6800 MB/s read and 5800 MB/s write, both over PCIe. Sequential numbers like these describe large sustained transfers; the responsiveness you notice day to day tracks random access more closely than the peak figures do.
Random access
SanDisk Optimus GX 7100 500GB is rated 760,000 IOPS random read and 1,200,000 random write; Western Digital WD_BLACK SN7100 500GB, 760,000 and 1,200,000. Random 4K access — many small, scattered operations — is what a drive does booting, launching apps and juggling everyday tasks, and it tracks that feel far more closely than the sequential figures above.
Price
SanDisk Optimus GX 7100 500GB is £89.99 (£179.98 per TB); Western Digital WD_BLACK SN7100 500GB is £106.99 (£213.98 per TB).
Endurance
SanDisk Optimus GX 7100 500GB is rated for 300 TBW and Western Digital WD_BLACK SN7100 500GB for 300 TBW — the total the maker warrants you can write over the drive's life. A typical desktop writes only a few terabytes a year, so either rating is many years of headroom; the figure matters mainly as a relative signal of how hard each is built to be driven.
DRAM cache
On the cache question: SanDisk Optimus GX 7100 500GB is DRAM-less, and Western Digital WD_BLACK SN7100 500GB is DRAM-less. The DRAM keeps the flash-translation table close, sparing a lookup on nearly every access; a drive without it leans on host memory or its own flash, which usually shows as slower sustained random writes rather than in the headline sequential numbers.
NAND, controller and warranty
On the flash itself: SanDisk Optimus GX 7100 500GB uses TLC, and Western Digital WD_BLACK SN7100 500GB uses TLC. NAND tiers count bits per cell — more bits pack more capacity into the same silicon but shorten write endurance and slow sustained writes, which is why QLC sits below TLC on lasting performance even when the sequential numbers match. Controller: SanDisk Optimus GX 7100 500GB's controller is not stated and Western Digital WD_BLACK SN7100 500GB uses the WD/SanDisk in-house Polaris 3 (4-channel, DRAM-less). The controller runs wear-levelling, error correction and the mapping table, so it shapes sustained and random behaviour as much as the flash does — though the model name alone predicts little without testing. SanDisk Optimus GX 7100 500GB carries a 5-year warranty and Western Digital WD_BLACK SN7100 500GB carries a 5-year warranty — the length the maker will stand behind the drive, and usually a proxy for the endurance it is rated to.
Which to buy
Against the other, SanDisk Optimus GX 7100 500GB is even or ahead on every tracked measure and behind on none, which is the one case where the choice needs no compromise.
Common questions about this pair
- Which is faster, SanDisk Optimus GX 7100 500GB or Western Digital WD_BLACK SN7100 500GB?
- SanDisk Optimus GX 7100 500GB states 6800 MB/s read and 5800 MB/s write; Western Digital WD_BLACK SN7100 500GB states 6800 MB/s read and 5800 MB/s write, both over PCIe. Sequential numbers like these describe large sustained transfers; the responsiveness you notice day to day tracks random access more closely than the peak figures do.
- How do SanDisk Optimus GX 7100 500GB and Western Digital WD_BLACK SN7100 500GB compare on random access?
- SanDisk Optimus GX 7100 500GB is rated 760,000 IOPS random read and 1,200,000 random write; Western Digital WD_BLACK SN7100 500GB, 760,000 and 1,200,000. Random 4K access — many small, scattered operations — is what a drive does booting, launching apps and juggling everyday tasks, and it tracks that feel far more closely than the sequential figures above.
- Which costs less per terabyte, SanDisk Optimus GX 7100 500GB or Western Digital WD_BLACK SN7100 500GB?
- SanDisk Optimus GX 7100 500GB is £89.99 (£179.98 per TB); Western Digital WD_BLACK SN7100 500GB is £106.99 (£213.98 per TB).
- Should you buy SanDisk Optimus GX 7100 500GB or Western Digital WD_BLACK SN7100 500GB?
- Against the other, SanDisk Optimus GX 7100 500GB is even or ahead on every tracked measure and behind on none, which is the one case where the choice needs no compromise.