Yes it's the lowest power usage mining algo out there. I am actually trying to build a enclosed rig which is more living room friendly when the guests or family arrive. Seems with adequate cooling you can easily do 5-6 GPUs in a server chassis without the temps going up or without the fans going max speed.
XMR however is not as easy as ETH to set up properly. The bios needs to be difficult and if you take the time to tune each GPU individually you can get decent power efficiency.
So it's a good thing that it's hard to tune because most lazy miners might just stay on ETH using Claymore. Should keep the difficulty low temporarily.... until the FGPA arrive again that is.
Fantastic! We should talk as I like 4U Monero builds. Delta fans in the front (3). You can use lesser fans, and this is what equalizes the temps across all cards, zip tied to the support beam that you can move towards the back 1/3 of the case in RoseWill cases like the RSV-L4500.
Place an APW3++ on the bottom/back of the case to the side of your motherboard. Stack something like a HP server PSU on top of the APW3++ with an X-adapter to supply power to a PICO PSU (eBay, 100 watt minimum) and one or two video cards/risers. Use dual 6+2 splitter cables to extend the length of the APW3++ cables to power all or most of the GPUs.
This Spotswood kit is really helpful for 4U builds, but the screws and parts are tiny (frustrating at first): https://bitcointalksearch.org/topic/fs-bracket-to-mount-7-gpus-at-front-of-rosewill-l4xxx-server-chassis-updated-1731197
Your first "Spotswood" build will leave you cursing, the second will be much easier. If you are of my age, you will need those reader glasses to handle the tiny screws. But his designs are elegant in some ways.
I had to build some "partner friendly" living room rigs. As far as she is concerned, they look like the amplifiers I used to have for Hifi. Sapphire Pulse Vega 56s, especially the Samsung memory ones give good results.
https://gyazo.com/d98e3651c436ab6cde03cd33b6eb7580
Tuning: run the miner (right now Team Red miner is working well post cnvR fork). Open up ONT. Open up GPU-Z, switch to the Sensors tab in GPU-Z. Change ONT settings on a card by card basis, watch GPU-Z closely. Save what works as a ONT profile on a card by card basis if you have the time. I also use and like the Brnstd Excel SoftPowerPlay table generator. With Team Red, more often than not you need to reduce mV settings rather than increase to get stability/higher hashes.
Edit: vBios tricks -- You can flash Reference Vega 56s with the same model/make Reference 64 bios, some debate whether this adds anything. You can flash the Sapphire Reference Vega 64 air bios to a Sapphire Pulse Vega 56 *Samsung memory* not Hynix memory card. There are at least four variants of the Sapphire Pulse Hynix Vega 56 bios and I would say don't waste your time on flashing/re-flashing these variants. So there really is not that much to do as far as bios modding on Vega cards. You will get more bang for the buck with the Brnstead SoftPowerPlay tables and then spending a little time tuning individual cards using ONT saved profiles, if that is an option. This is not a situation like the RX 480 8GB Samsung cards where, with a bios mod, one minute you were doing 700 kH/s and then the next with the right bios mod you jumped to 860 kH/s on Cryptonight. I have not seen huge gains on Vega cards with just reflashing BIOS versions.