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I got a SSD for Christmas and it came with the option to have it installed internally or externally. I'm wondering if I have it setup as an external hard drive, will there be any major performance differences? Internally, the SSD would connect through SATA. Externally, the SSD would be converted from SATA to USB. I should also note that my motherboard uses USB v2 and SATA v2.

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In practical terms USB 2 is 25mb-30mb/s and SATA 2 is close to 300mb/s. –  cybernard Dec 25 '13 at 7:35
    

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up vote 16 down vote accepted

Yes, it would make a difference.

USB 2 has a theoretical max of 480 Mbit per second. Actual available bandwidth is about 30-40MB/sec, depending on the chips and the drivers used. Part of this is due to 10% bandwidth reserved for USB1 communication, part of it is because the USB protocol has a lot of overhead.

SATA is less flexible (e.g. you can only connect harddisks, port multipliers and CD/DVD/BR-ROMS), but it has much less overhead. It also works at a much higher speed (SATA-II at 3.0 Gbit per second). The result is a maximum thoughput around 270MB/sec. (Actual test values from a ICH9 and SATA drives on tech sites).

35MB/sec vs 270MB/sec. That makes SATA-II over 7 times as fast on thoughput alone.
And since there is also less overhead the latency will also be lower.

TLDR; Connect it via SATA. Or if you want it externally, get an eSATA connection.

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Internal it is. –  ub3rst4r Dec 25 '13 at 20:53

The difference is huge:

  • USBv2 has a speed of 480 Mbit/s
  • SATA2 has a speed of 3072 Mbit/s

SATA 2 is almost 6.5 times as fast.

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The internal option would be faster. As per Wikipedia the theoretical maximum speed is 480 megabit, with effective throughput of 280 Megabit/second = 280 Megabit per second. SATA 2 is 300 MEGABYTE per second, so almost 10 times the "real world" maximum speed. Depending on the SSD it would probably max out between 180 and 550 Megabytes per second, so definately SATA 2

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