Sata III ssd on Sata II
- Thread starter axelblaze
- Start date
Even on SATA II, you're still looking at twice best-case platter read speeds, and three times average sustained read speeds. Obviously, having SATA III would be an improvement, but an SSD now would still be a huge improvement.
Solandri
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- Jan 4, 2012
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The bigger concern with a SATA2-only computer is whether or not the BIOS supports AHCI mode. You need AHCI for NCQ (native command queuing) to work. The biggest speed increase from a SSD isn't sequential transfers, which is what SATA2 limits (300 MB/s vs 600 MB/s on SATA3). It's from random transfers of small files.
A modern HDD can hit about 150 MB/s on sequential transfers, so a SSD is only 2x-4x faster. But 4k random read/write speeds on a HDD are about 1.5 MB/s at best. On a SSD they're about 15-30 MB/s, which is 10x-20x faster (actually more since most HDDs are down around 0.8 MB/s). With NCQ, the SSD can queue up multiple random transfer requests (that's what the QD you see in some of the disk benchmarks are - queue depth) and complete them without needing further instructions from the computer. By doing this, SSDs can typically hit 150-300 MB/s at random 4k transfers with a QD=16 or 32. So at these types of tasks (e.g. reading lots of small files to load a game) they can be several hundred times faster than a HDD.
If you're running the SSD in SATA mode instead of AHCI, you lose NCQ and the random 4k read/write speeds will plod along at "only" 15-30 MB/s. The drive will "only" be 10x-20x faster than a HDD instead of hundreds of times faster.
A modern HDD can hit about 150 MB/s on sequential transfers, so a SSD is only 2x-4x faster. But 4k random read/write speeds on a HDD are about 1.5 MB/s at best. On a SSD they're about 15-30 MB/s, which is 10x-20x faster (actually more since most HDDs are down around 0.8 MB/s). With NCQ, the SSD can queue up multiple random transfer requests (that's what the QD you see in some of the disk benchmarks are - queue depth) and complete them without needing further instructions from the computer. By doing this, SSDs can typically hit 150-300 MB/s at random 4k transfers with a QD=16 or 32. So at these types of tasks (e.g. reading lots of small files to load a game) they can be several hundred times faster than a HDD.
If you're running the SSD in SATA mode instead of AHCI, you lose NCQ and the random 4k read/write speeds will plod along at "only" 15-30 MB/s. The drive will "only" be 10x-20x faster than a HDD instead of hundreds of times faster.
Solandri
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I can't find that model, but the ga-78lmt-usb3 appears to support AHCI (there are multiple versions of the motherboard so I can't be sure they all support it). If that's the right model, it's probably worth trying. Just hop into your BIOS settings and look for a SATA mode setting, and see if it has an AHCI option (IDE, SATA, AHCI, RAID are common options). As I explained, most of the speedup from a SSD is from how quickly they read/write small files, where the SATA2 speed limit is not a factor.
Be aware that if you installed Windows with AHCI turned off (BIOS is in either IDE or SATA mode), it will not boot after you turn AHCI on. Here are some guides for fixing this without reinstalling.
http://www.tomshardware.com/answers/id-1634729/boot-switching-driver-ahci-windows.html
http://www.neowin.net/forum/topic/987378-how-to-switch-from-ide-to-ahci-without-repairingreinstalling-windows/
http://forums.pcper.com/showthread.php?444831-HOWTO-enable-AHCI-mode-after-installing-Windows
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