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Silver rectangular 2.5 inch bare SATA hard drive with exposed circuit board

Seagate

Seagate ST9640423AS 640GB 5400 RPM 16MB Cache SATA 2.5" laptop hard drive

SKU CH-R2KS-CFRC0 MPN ST9640423AS

A 640 GB 2.5-inch SATA laptop drive spinning at 5400 RPM with 16 MB cache and 9.5 mm height

  • Total capacity640 GB
  • Interface typeSATA
  • Form factor2.5 in (6.35 cm)
  • Packaging typeBare Drive
  • Cache memory16 MB
  • Average seek time11 ms
  • 640GB capacity stores large media libraries and backups
  • 5400 RPM spindle speed balances quiet operation with reliable throughput
  • 16MB cache accelerates frequent read and write operations
  • 5 inch 9.5mm form factor fits standard laptop drive bays
  • SATA interface enables direct replacement in compatible notebooks

Capacity and Form Factor

The Seagate ST9640423AS is a 640GB 2.5-inch internal hard drive designed for laptop upgrades or replacements. It operates at 5400 RPM with a 16MB cache and connects via a standard SATA interface.

Suitable Uses and Limitations

This drive suits users restoring older notebooks or needing affordable bulk storage for documents and media where high speed is not critical. It is not suited for buyers who require faster boot times, quicker application loading, or lower latency than a 5400 RPM mechanical drive can provide.

Deciding Specification

The 5400 RPM spindle speed is the single figure that determines whether this drive meets your performance expectations. Average seek time is 11ms, average write time is 13ms, and average latency is 5.6ms.

How it compares

Measured against everything we stock in 2.5-Inch Internal Laptop HDDs, at today’s prices. Recalculated every night.

Price $57.99
Cheaper than about 58% of the 645 comparable items (median $66.99).
Total capacity 640 GB
Higher than about 76% of the 419 comparable items (median 320 GB).
Price per TB $90.61 per TB
Cheaper than about 83% of the 416 comparable items (median $233.48 per TB).

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Specifications

Product
Brand nameSeagate
Product lineMomentus
Model nameST9640423AS
Total capacity640 GB
Performance
Average seek time11 ms
Mean write time13 ms
Mean latency5.6 ms
Rotational speed5,400 RPM
Storage
Cache memory16 MB
Ports & slots
Interface typeSATA
Size & build
Form factor2.5 in (6.35 cm)
Max height9.5 mm
Maximum width69.85 mm
Maximum length100.35 mm
Shipping weight0.45 kg
Package size152 × 102 × 51 mm

Questions about this item

What is the first limit reached during sustained use with the 5400 RPM spindle?

Sustained throughput is limited by the 5400 RPM spindle and 16MB cache, which together cap sequential transfer rates below faster drives.

How much noise and heat does the drive produce when running all day?

The 5400 RPM motor and 9.5mm height typically yield low acoustic output and modest heat, suitable for continuous laptop operation.

What existing laptop interface is required for the SATA connection to work?

The notebook must provide a standard 2.5-inch SATA bay with a 7-pin data and 15-pin power connector.

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