Samsung’s storage division has quietly introduced a new high-performance 2.5” notebook hard drive with an impressive 640GB capacity: the HM640JJ. This two-platter drive runs at 7200RPM with a 16MB cache, SATA II interface, and a three-year limited warranty. We take a look to see how it compares to other high-performance notebook hard drives.

- Unformatted capacity: 640GB
- Interface: SATA II (3.0Gbps)
- Spindle speed: 7200RPM
- Cache: 16MB
- Average seek time (typical): 11ms
- Data Transfer Rate/Media to/from Buffer (Max.): 189MB/s
- Data Transfer Rate/Media to/From Host (Max.): 300MB/s
- Drive Ready Time (typical): 4 sec
- Non-recoverable Read Error: 1 sector 1014 bits
- Acoustics: Idle: 2.6 Bel
- Acoustics: Performance Seek: 2.8 Bel
- Height: 9.5mm
- Weight (avg.): 119g
- Power: Seek (typical): 2W
- Power: Read/Write (typical): 2.5W
- Power: Idle (typical): 0.85W
- Power: Standby (typical): 0.2W
- Power: Sleep (typical): 0.2W




















- Solid overall performance
- Stacks up to competitors
- Large 640GB capacity
- Falls behind in server-style disk load