Building the ultimate 18 GPU mining rig with the following :
1 - 18 GPU Nvidia RTX 3090 at 120 MH/S at 300 Watt :
https://ebay.us/QrDNQp fby=a194aefb-325d-4cb1-9234-a3c5fb01070f
is there anything missing i should add ?
Well this ebay link doesn't exist, if you could find a rtx-3090 in todays market for a real non-used card, it would be $10k, maybe more, you must wait for price to drop back down below $1k
I run this RTX at about 120watts, above that the heat goes above 72C, and I don't run my cards hot ( kills them ), maybe see about 100MHS, that's a whopping ETH $10/day on $2/day power, payback at today price, longer than the life of the card.
Like the people here say, I would do a 1200W gold power supply, and each have 4 cards;
U really need to propose your budget, rather than your wishlist. Then people would tell you what you could buy in todays market, rather than what you would like to have
Most mobo's only support six gpu's, is a limitation in linux; mobos are cheap; also if you use 8 gpu racks, you can space out your cards so they can ventilate
In the winter no problem, run at 180W, turn up the clock, if you are intending to run at 300W, do you have central air-con, or are you in the north-pole?
Have you actually done this before? GPU mine?
Why not start with a single GTX-1060 6gb, and learn, and then scale up and see what actually works.
If you haven't mined before, understand that you must take everything apart every 3 months and clean the cards down to the raw boards, I don't care where you operate they collect dust&goo, and in time they short themselves out, unless cleaned. Which why you don't want 18 cards on a dense rack, maintenance is impossible, wiring nightmare, beyond the problem that it will not work.
Like the guys here say, with 3 rigs when you working on one card, you still would have 12 running, with your strategy having a problem with once card and your out of biz. But like I said, these cards are so damn expensive, and everything else is so cheap, I would do 4 cards per rig, and space them cards out for cooling.
IMHO this post is BS, as the RTX-3090's in new condition are not available anywhere on earth.
I run RTX-3070's rigs, got them cheap last year, see about 51MHS, I run six cards per rig, and keep them cool right now, I limit to 115 watts. Like I said above 72c ontinuous the cards always die, I'm seeing about 310MHS, but they run cool and strong. I clean them every six months, which means complete disassembly, and cleaning, and new thermal grease.
I even run air-purifiers in my mining rooms, and I still see about 10% death rate of cards annually, most are newer cards. Better have a solder re-work station on on-hand small caps and voltage-regulators like to pop, when the cards get about 74C.
Expensive hobby, only argument is your not buying crypto from an exchange your mining your own 100% privacy, other than that total waste of time & money. Think about heat dissapation in the summer, 18 rtx-3090's at 300W, that's enough power to run an industrial over to melt gold. Where in the hell are you going to dissipate all that heat? Air-Con?
Let's see, your cards will cost you $180k, have you really thought about how many decades your ROI will be??
I think most people that own cards already are on hold, until the prices come back to earth, now its appearing to be years, which means these RTX-3090's will even become more expensive.
Lastly, if you can't repair your cards, you really shouldn't buy them.
Yes, like the guy here say's the future of ETH mining is going to be over before the GPUS become available.
...
On a side note, RTX-3070's can hack 2500M/keys/sec, running with a 64gb bloom-filter of 300M addresses, I can do 100T/keys/sec on each card, so my RTX rigs actually hack bitcoin, better than minning ETH, but this is just an example of how these RTX cards can be re-deployed in the future post ETH mining; The payback is one high-value address per card 1,000 days, on paper, but they do better.
The probelm with all GPU mining is that the CHINESE have boxes now that kill these cards, they have ASIC's with 10gb that can attack any crypto-algo on the planet; This is what happened to EQUI-HASH mining it was killed by Chinese mining boxes, and soon Eth will be toast, E-15, Z-15, ...
These last two are the jokes to end all jokes, now I know this post is 100% bull.
Nobody runs windows
Nicehash, are you joking, they don't even let you mine to your own private key, they keep your mining winnings in their address, and they let you spend your money at their company store, nicehash is the biggest ripoff on the crypto planet.
Now I know for a fact you have never mined anything.
[moderator's note: consecutive posts merged]
. Great cards that love fujipoly and extra backplate heatsinks. 3080 would be a better idea, at msrp or not. My 3090s won't go above 123.7. Try and stay tuned for July, unless mining something besides ETH. 
