ALL the 3 PCIE connectors are needed to be connected to power supply on each hash board since it is based on serial power solution and there is no DC/DC inside the miner. Including the one PCIE connector on control board, there are 28 connectors in total.
Several PSU will be needed to support the miner, anyone spare PCIE connector from PSU will be connected to control board.
But be sure to
power all the other PSU first and power on the last PSU which control board is connected in the end. this is very important!!
You can use as many PSUs as you want as long as you don't have multiple PSUs powering the same individual board (of which there is 9).
Do all PCI ports need to be powered? Or will it run with 2 on each board?
2 is fine, still only about 165W per PCI-E.
Are you certain that using 2 is fine? The product description page says all three are required. It may be that each PCIe plug powers a specific set of chips; the 3 PCIe connectors may not share a common power bus at all as in, say, the S3 design. Without knowing the actual S5+ design, or having an actual unit to look at, saying "2 is fine" is only speculation at this point unless something more is known than what bitmain has disclosed so far.
Bitmain could confirm this here, but they aren't posting much these days. If anyone already has a unit, they could also confirm whether using 2 out of the 3 connectors works and post here.
What Bitmain customer Service told us was we have to use all 3 connectors for each board, As my understanding if each board need at least 382W(3436/9), in average each connector should be bear
[email protected] , and if it works using only 2 connectors instead that will be
[email protected] for each connector , it is high risk to heat up or burn your cables if they are not good enough.
This still doesn't answer the question of whether all 3 are *required* by design, or can 2 be used if the cables can handle the increased current?
BTW the power requirements aren't as high as you mention: 3436W quoted by bitmaintech is at the wall, using a 93% efficient PSU. So the DC power to the S5+ would only be 3436*0.93 or 3196 watts, or 355W per board. *If* the design allowed the use of 2 connectors per board, this would put 178W per connector (14.8A). This isn't bad, considering S3+ units can easily be powered with 2 PCIe cables and those use around 355W as well.
If you could, please elaborate for folks.
We are an unruly bunch, and while I plan to follow the rules, it would be great to know and understand the reasoning on a couple of these points. I do not plan to debate them, I want to understand, so please take your time, and explain them for us. Most / many of us are involved in the purchasing of miners for one of two simple reasons or both:
A. We like to gamble and take a little risk to earn.
B. We have a bit of an anarchist deep down who truly believe this technology will disrupt the monetary systems.
The points I see which require further clarification:
1. Why does the controller board need to be powered on last? Is it a matter of establishing proper communication with the serial chains? Did you learn something with the S5 which causes the three modules in series to have issues?
1A. I have a follow up regarding this to say, if it is truly important to power up the controller last, then why not require the controller to be powered from a separate power source? Will it void the warranty IF the controller board is powered by a separate power source? I can see this being dangerous if that power source failed since none of the fans will run and I assume all of the hash boards will melt down.
2. The instructions sent with the miner call for you to inspect each heat sink on the hashing boards to make sure none have fallen off during shipment. How do you recommend we do so without removing the hash boards? You can't see them all by popping the fans off.
My comments on using two PCI connectors are if you do it without understanding what you are doing and measuring the current being drawn you are simply asking for trouble. Why risk it? Why take more of a chance of causing cable issues and melting down your investments or worse, burn down your home / business? We stress our cables simply connecting them. Most of the break out board designs cause stress when you have all cable locations populated and then simply sit the miner and the power supply on the shelf and connect the cables. Further consider the heat in the US and maybe wherever you live. Unfortunately for me, we aren't done with 45 c and higher ambient (heat index) days yet and these babies are going to be pushed to their limits. Be smart and use all three. It is a safety factor as well as BITMAIN aren't going to cover your warranty when you charcoal a single PCI connector on the hash board.
this seems hard to do... anyone knows where to purchase those 6 pin pcie cables awg 16.. ? 
