My Antec case has a purple snap-in module to easily accommodate a fan that sits directly in front of the HD's. The more I'm learning about case cooling, the more it makes sense to get such a fan. The questions I have are: 1. Are there fans that are designed to blow into the case, over the hd's, as well as fans that are designed to blow out, taking the air out from the case, or are they the same fans with a switch, sort of like a ceiling fan with a reversible option? 2. Is there any consensus as to which way is better -- blowing in over the hds, or out like an exhaust?