Iain said:
logicearth said:
I'm going to chime in with just one tidbit of information.

...

Granted, HDDs are barely capable of reaching SATA 1 speeds.
Even 7200 rpm SATA III drives????????
Yes. The only time an HDD will even get close to SATA 2 speeds is during the initial burst when it is buffering the cache embedded on the HDD, after the cache is filled the speeds go back down to SATA 1 speeds. HDDs can not sustain SATA 2 speeds only in burst while the cache is empty. How long it stays in that burst speed depends on the amount of cache the HDD has.

That is why you normally see "16 MB" or some other value in the HDD description along with the speed, that is the amount of cache it has.

SATA 3 (or SATA 6gb/s) was made solely for SSDs while HDDs can be connected to it they will get no speed benefits from it. Other then a few new improvements in NCQ but not much more.

https://en.wikipedia.org/wiki/Serial_ATA
As of April 2010 the fastest 10,000 RPM SATA mechanical hard disk drives could transfer data at maximum (not average) rates of up to 157 MB/s, which is beyond the capabilities of the older PATA/133 specification and also exceeds a SATA 1.5 Gbit/s link.
A 10,000 RPM HDD is barely faster then a SATA 1 connection could provide.