I'd actually go for the Be Quiet you know, it seems to have better efficiency, more connectors and it offers 420W on two split 12V rails as opposed to 425W on four split 12V rails.
I don't see any reason to pick the OCZ over the Be Quiet. The Be Quiet 530W seems to be a new winner! Shame none of the big tech sites have reviewed it.
Both of these cards will be able to handle a 5830 easily if not two.