Crucial M4 256GB SSD review

A high-speed SSD that makes other drives look overpriced

Price when reviewed 

Following hot on the heels of Intel’s brand new 320 Series and 510 Series SSDs, Crucial’s M4 SSD has its sights set firmly on the high end.

A notable first for Crucial is the move to 25nm NAND flash, rather than the 34nm chips found in the M4’s predecessor, the RealSSD C300. The higher data density promises lower manufacturing costs and increased performance across a range of capacities from 64GB to 512GB.

Crucial has also used a new Marvell 6Gbit/sec controller, similar to that found in Intel’s 510 Series, which should deliver an additional performance benefit over the previous generation.

In AS SSD’s synthetic benchmark tests, the 256GB M4 drive averaged sequential read speeds of 416MB/sec and write speeds of 257MB/sec. Unlike its Intel-branded rivals, random access performance was impressive too: AS SSD’s multithreaded 4K read and write benchmarks saw the Crucial average 159MB/sec and 204MB/sec – over twice as fast as the Intel 510 Series.

Crucial M4 SSD

Windows performance was equally strong. Writing 1.5GB of large files to the M4 saw an average write speed of 328MB/sec, while read speeds hit 284MB/sec. Small file performance is always slower, but with read and write speeds of 181MB/sec and 158MB/sec respectively, the Crucial M4 is still as quick as solid-state storage gets.

The real coup is the price. Thanks to the reduced manufacturing costs of 25nm flash memory, projected pricing sees the 256GB drive cost a very reasonable £1.46 per gigabyte – far cheaper than Intel’s latest models.

The M4 still isn’t as cheap as Kingston’s SSDNow V100, which remains the best budget drive on the market at £1.17 per gigabyte. But if you’re looking for an affordable SATA 6Gbit/sec model with cutting-edge transfer speeds, Crucial’s M4 is a high-performance hit.

Price when reviewed 
374(£374 inc VAT)


Capacity 256GB
Hard disk usable capacity 238GB
Hard disk type SSD
Cache size 256MB
Spindle speed N/A
Seek time (ms) 0.1ms
Cost per gigabyte 146.0p

Noise and power

Peak noise level N/A

Performance tests

Write speed small files 157.5MB/sec
Write speed large files 327.7MB/sec

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