I have 5 EVGA G2 850W units powering 10 S3/S3+ no problems; no need to use paperclip to short the pin on the motherboard connector either - the PSUs come with a adapter that will short the pins. You only need to use 2 PCIE power cables per S3 - no need to use 4 per miner.

Also using EVGA G2 750W units to power AM Prisma (2 per Prisma)

If you happen to be in USA; Amazon has the best prices on the EVGA G2s and their MiR will cover up to 2 PSUs.

I have used the Dell 750W Server PSUs w/ breakbout boards; they get pretty hot; even with the fan turned up.  I sold 2 of tyhem on eBay - kept 2 for spares; so I could setup miners in my office before they go to mining room in basement.