These work very well - 2400w and 94% platinum efficiency.  $159 + around $40 for the ATX adapter from Parallel Miner.  Link is below.

http://www.parallelminer.com/?wpam_id=1

https://i.imgur.com/9SQ57nv.jpg

We now have these running our 8x 1080 Ti rigs by themselves, without the additional power supply and they seem to run just fine.

https://i.imgur.com/XXscuNK.jpg