Ok, but that's another thing I didn't understand. Why are people still recommending the 830s when there's a new version of them out?
The newer series doesn't really improve much. In fact, in real-world circumstances you'll never notice any difference between the two. The 830 dropped in price when the 840 came out, but the model's speed and reliability are the same... so, when there's really no functional difference between them, there's no reason to go for the more expensive one just because it's newer.