Cooling hard drives in a Silverston ST17

[oberbimbo]

My HTPC is working nicely, but now that I have 5 drives in it (1 500G Samsung, 4 1TB GPs) the hard drives are getting pretty hot.

I am running with the Etasis Fanless PSU and the original 2 case fans at 5V (they are just too noisy at 12V but barely move any air at 5V). So now I am wondering what I could to cool down the harddrives.

Is it better to mount fans in front of the drives, creating what would likely amount to positive pressure of sorts or should I simply use better case fans? If so, what ~20db 80mm case fans would move the most air?