I have a bunch of nice atx power supplies laying around from gpu mining, is there any way I can leverage those?

yes   you need this

  this tricks the psu into turning on.

http://www.ebay.com/itm/261302980079?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649


  then go to this guy

https://bitcointalk.org/index.php?topic=74397.msg6783806#msg6783806




you will be far better off and you will spend  less then70 bucks.    you will be able to power 3 blades.

  as cablez has 3 plugs  2 sets have 6 plugs.


I have all the gear you have and I have the better gear.  night and day difference.

by the way your gear will pull 10 to 20 watts more as the psu you picked is under 80% more like 70%


you should reall get the cables by cablez