Ok, info for future reference. The OCZ modular range (ModXStream) has no molex sockets on it - at least the 600W doesn't. It does come with PCI-E 6-pin to molex male cables, two of them. One of these is now powering all 3 of my case fans, by use of a relay between each fan's male & female molex jacks. The final fan's male molex is dangling uselessly.
I think that just about does it. My rig is up & running. Next upgrade (probably a few years away, considering the state of my credit card) is gonna involve investment in a much larger motherboard - I don't like fiddling about with the tiny X58M, especially when I've got my entire head in the case to do it. Just seems like a waste, though there's so much cable that little space was wasted.
This experience has left me aching, bruised, bleeding & frustrated. Above all, elated. I actually sleep better with the soft hum of my new rig (which I've named Serenity), and the pretty dance of the LED patterns shining through my operational fans. I don't think I'll ever let someone build my computer for me again. Thanks again for the assistance, I'd have less hair if I didn't have this resource. It's like having a computer monkey right there with you.