# Sata III compatible with II?



## pengyou

quick questions....are all SATA III hard drives compatible with a SATA II controller? Will SATA III provide faster boot up times? and if a hard drive says it has 6 gb/sec does that automatically mean SATA III?


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## epshatto

Yes, the standards are backward compatible. You can plug a SATA III drive into a SATA II connector.

But note that the throughput is always limited to the slowest bus speed.

In other words, if you do the above, you won't have a SATA III throughput. The speed will be defined by the SATA II motherboard controller. 

I would figure a 6 GB/s hard drive would almost certainly be SATA III. I don't know what else it would be as it's definately not a PATA standard and SATA II doesn't get to that speed.

Also as far as bootup times, it depends. Again, you have to plug a SATA III drive into a SATA III connector in order to hope to be able to get the 6 GB/s throughput. But you're not likely to actually reach those speeds in most circumstances. There's some thought out there that a SATA 3 SSD can get you great boot speeds, but I've heard different things about that.


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## LMiller7

The interface sped isn't the only factor in hard disk performance. In many cases it isn't even particularly important. Other factors include the internal transfer rate, head seek time, and rotation latency. The major factor for conventional drives effecting boot time will be seek time, and SATA III does nothing for that.

AT the present time SATA III will be most beneficial with SSD's. Most other drives aren't fast enough to benefit much.


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## epshatto

LMiller7 makes a good point about the seek time. Usually the speed of a drive is measured in RPM and not bus speed anyway. 

So if you didn't want to invest in a SSD say, your best bet would be a 10,000 RPM platter drive to use as a boot device.


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## gcavan

Are all SATA III hard drives compatible with a SATA II controller? Yes

Will SATA III provide faster boot up times? Only if you have the OS installed on a SSD

If a hard drive says it has 6 gb/sec does that automatically mean SATA III?Theoretically, yes. However, only the fastest conventional hard drives can saturate the bandwidth of even first generation SATA (~150MB/sec) None can saturate SATA 2 (~300MB/sec) At this time only SSD's will benefit from SATA 3 speeds (600MB/sec)


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