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I understand the difference between SATA-2 and SATA-3, and what L1-3 cache are. But I am trying to choose between two internal harddrives. Both are 1TB capacity, with 7200RPM. The difference between the two option is that one is SATA-2 with 64MB cache, and the other is SATA-3 with 32MB cache.

So what would be "better"/faster between those internal harddrives? I will use the harddrive as a second internal (slave) HDD. Mainly for storing and transferring large files.

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up vote 4 down vote accepted

I was going to write an answer saying if speed for transfer was important for the large backup files then use SATA-3, but after looking at this paper http://www.seagate.com/docs/pdf/evolution_to_sata_6gb_storage.pdf I'm not sure if the interface speed is going to make a difference, because it is the hard drive that is the limit.

Why Is SATA 6Gb/s Needed Now?
Today, hard drives for PCs don’t seem to be pushing the limits of the SATA 3Gb/s interface. The highest-performance desktop drives on the market deliver about 1.5Gb/s in sustained data transfer rates. Add another 0.5Gb/s in command overhead that is not available for general data transfers, and you still have 1Gb/s of headroom before you bump into the 3Gb/s ceiling. But it won’t be long before hard drive technology catches up to the SATA 2.0 standard. Seagate estimates that hard drive transfer rates will exceed 2.5Gb/s by mid-2011. Add in the 0.5Gb/s command overhead, and the SATA 2.0 standard is out of gas.

The PDF was dated January 2010.

The did do a comparison between SATA-2 & SATA-3, and 32MB & 64MB, but unfortunately, they compared slow interface and less cache to faster interface and larger cache. It would have been interesting if they did the comparison you were looking for.

Unfortunately, I think looking at the hardware websites and getting independent numbers on the actual throughput is the only true way to know.

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Cache can have a big difference on a drive speed when used for routine or repetitive data transfer. SATA-3 also brings it's advantages. Personally I'd go for the 64MB one if you have backups and all that stuff to make.

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I'd go with the larger cache. The speed difference is only for bursts, and iirc it's a number your disk will rarely reach. Being able to keep more data cached should help a lot more.

But why choose? You can have both for only $70:
http://www.newegg.com/Product/Product.aspx?Item=N82E16822136742

And what I'd really like to get right now is a Momentus XT Hybrid disk. They're currently $120 for a 500GB model, but it should knock the pants off either disk you posted.

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