These PSUs could still support 5 if they're right at or under 500W, but for safety (and marginally improved efficiency) it would probably be better to run 4 per. 50 would then require 13, or 12 if you did some clever load-balancing. At that range, you're in the second-tier price break of $57 per board. 160 cables would be $560 to $720 depending if you wanted 18" or 36" or a mix of both.
We're in preorder stage now for the boards; PCBs are expected to arrive about the 22nd and we'll have the rest of parts by then to start manufacture for shipping by the 25th. If you get in the queue right now, we'll probably be shipping your boards and cables on or before the 28th.
If you're interested in a purchase or want to discuss further, email [email protected] and we'll get you set up.
$40 per PSU + shipping, have plenty. On hand now, and they work great with the proto boards I have gotten from sidehack
Are they on the website? I do not see them. I need 13 please.