Hmm... Without manufacturer documentation, it's hard to say what those would be specc'd at. I'd recommend hacking a wiring harness with extra leads for a multimeter (or two-one for 5v & one for 12v) and watching for any voltage droop with all the drives going. Even 15k RPM 2.5" drives only use ~2A I think 4 normal drives + 4 SSD's would not use a terrific amount of power.