Ordered another Perif/4-pin molex cable recently, just wondering if I can simply plug it in to a SATA port on the PSU & use it, or if those are wired differently? 
I got it to put in place of the Molex cable that has that stupid antiquated tiny FDD plug at the end (the one I'm getting as all 4-pin molex), but if I can use both, that would give me more places to plug fan splitters in to (which I am running out of).  Need the extra plugs if possible, so would this work or are they incompatible?

EVGATech_GabrielT
This will be fine, you can use SATA on PERIF or vice versa with no issue.

Awesome, just wanted to double check, thank you for the quick answer ^_^