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Silver 3.5 inch SATA hard drive with green circuit board

HGST

HGST 0A37991 640GB 7200 RPM 16MB SATA 3.0Gb/s 3.5" internal hard drive

SKU CH-K55H-J7M4N MPN 0A37991

3.5-inch desktop hard drive with 640 GB capacity, 7200 RPM spindle speed and 16 MB cache over a SATA 3.0Gb/s interface

  • Total capacity640 GB
  • Interface typeSATA 3.0Gb/s
  • Form factor3.5 in (8.89 cm)
  • Rotational speed7,200 RPM
  • Cache memory16 MB
  • 7200 RPM spindle speed delivers responsive desktop performance
  • 640 GB capacity stores documents, photos and media files
  • 16 MB cache buffers bursts for smoother data transfers
  • SATA 3.0 Gb/s interface connects to standard desktop motherboards
  • 5 inch form factor fits typical desktop drive bays

Capacity and interface

The HGST 0A37991 is a 640GB 3.5 inch internal hard drive built for desktop systems. It spins at 7200 RPM with a 16MB cache and connects through a SATA 3.0Gb/s interface. The drive arrives new in retail or OEM packaging depending on supply.

Who this suits

This drive fits older desktops or replacement scenarios that specifically require a SATA 3.0Gb/s connection and a 3.5 inch bay. It is not suited for systems that only accept 2.5 inch drives or newer SATA revisions beyond the stated 3.0Gb/s specification. Buyers needing higher capacities or faster transfer rates should look at other options.

Deciding specification

The SATA 3.0Gb/s interface is the single specification that determines whether this drive will work in a given system. Verify that the motherboard or controller supports this exact revision before purchase.

How it compares

Measured against everything we stock in 3.5-Inch Internal Desktop HDDs, at today’s prices. Recalculated every night.

Price $77.99
Cheaper than about 60% of the 4,938 comparable items (median $107.99).
Total capacity 640 GB
Lower than about 74% of the 2,372 comparable items (median 2 TB).
Price per TB $121.86 per TB
Pricier than about 68% of the 2,365 comparable items (median $62.21 per TB).

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Specifications

Product
Brand nameHitachi GST
Product lineDeskstar
Model nameHDT721064SLA360
Total capacity640 GB
Performance
Rotational speed7,200 RPM
Storage
Cache memory16 MB
Ports & slots
Interface typeSATA 3.0Gb/s
Size & build
Form factor3.5 in (8.89 cm)
Shipping weight0.39 kg
Package size25 × 25 × 25 mm

Questions about this item

How does the 7200 RPM spindle speed affect everyday performance?

The 7200 RPM speed provides faster data access and higher sustained transfer rates than slower desktop drives, improving responsiveness when loading applications or copying large files.

What does the SATA 3.0Gb/s interface mean for real-world throughput?

The SATA 3.0Gb/s link caps the maximum burst transfer rate at 3.0 Gb/s; actual sustained speeds are lower and depend on the drive’s internal media rate and system overhead.

Will this 3.5 inch drive fit a standard desktop drive bay?

Yes, the 3.5 inch form factor matches the standard internal mounting dimensions used in most desktop computer cases and drive cages.

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