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Difficulty: MediumStorage Devices and Interfaces

A desktop technician is configuring a workstation for a CAD designer who requires solid-state storage capable of sustained read performance exceeding 2,500 MB/s. The technician installs a 2.5-inch solid-state drive (SSD) connected via a SATA III cable interface. After OS installation, benchmark testing shows drive throughput capping at approximately 550 MB/s. Which of the following explains why this drive cannot meet the designer's performance requirement?

  1. The SATA III host interface has a maximum theoretical bandwidth limit of 6 Gbps (~600 MB/s).Answer
  2. B
    The 2.5-inch form factor requires an M.2 key adapter to activate PCIe NVMe protocol speeds.
  3. C
    The motherboard storage controller is operating in AHCI mode instead of RAID 0 mode.
  4. D
    The SATA power connector is supplying insufficient wattage to enable high-speed bus communication.

Answer

The SATA III host interface has a maximum theoretical bandwidth limit of 6 Gbps (~600 MB/s). To achieve speeds exceeding 2,500 MB/s, an NVMe SSD utilizing PCI Express (PCIe) lanes is required.
SATA III (6 Gbps) has a maximum theoretical data transfer rate of 600 MB/s. Due to protocol overhead, real-world maximum throughput maxes out around 550 MB/s. To achieve throughput over 2,500 MB/s, the system requires an NVMe drive connected over PCI Express (PCIe) lanes.

Step-by-Step Solution

1
Analyze the performance requirement versus the selected hardware interface.
The target requirement is >2,500 MB/s, while a SATA III interface drive was installed.
SATA III (Revision 3.0) interfaces operate at a maximum signaling rate of 6 Gbps6\text{ Gbps}. Accounting for 8b/10b encoding overhead, maximum real-world throughput is ≈550 MB/s−600 MB/s\approx 550\text{ MB/s} - 600\text{ MB/s}.
2
Determine the necessary interface standard to meet the requirement.
PCIe-based NVMe storage is required.
PCIe 3.0 x4 provides up to ≈3,940 MB/s\approx 3,940\text{ MB/s} and PCIe 4.0 x4 provides up to ≈7,880 MB/s\approx 7,880\text{ MB/s}, which easily satisfies the 2,500 MB/s requirement.

Key Concept

SATA III interface bandwidth limitations versus PCIe NVMe throughput capabilities.
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Topics

Storage Devices and Interfaces

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