Here is the answer - posted to you in the s9 thread also:

https://bitcointalk.org/index.php?topic=1007440.0

But you simply don't have enough space to solder all wires to the PSU, you would need to build your own fanout connector.  And I would def make sure to use all 6+ and 6- connectors so you don't melt down the PSU's connections!


(for reference I Google'd   IBM 2880W pinout site:bitcointalk.org  and it was the 8th result down titled "Help starting an IBM 2900W PSU - Bitcointalk" )