You did NOT take the total system cost into account.
Try adding $40-$50 to the price of each card THEN compare - and that's being optimistic as I don't think you can build a viable *8 slot* system for $320. It's hard enough building a viable *6 slot* system for $320, if at all possible.
Dual mine of DCR does in fact impact ETH hashrate - that's been WIDELY reported on the Claymore dual mining thread - though it's not a big impact, 10-20% per most of the reports.
I do agree that relative profitability can vary - ETH in the last week has kicked up a lot more than ZEC has as a percentage, which is giving a bigger boost to ETH mining than to ZEC mining which is at least for the short term boosting the profits on AMD cards more than NVidia cards, at least 'till folks start building enough rigs to drive the diff up to match the price increase.
It would have been interesting to see how the numbers compared a month ago, when both ETH and ZEC were a lot lower priced and fairly CLOSE on price (and both had a bit less network hashrate).
By the way, the figures i reported for AMD are quite conservative, and definitely include the slight impact of dual mining
So here i am going to add 50$ on top of each card:
1) ASUS Dual GeForce GTX 1070 OC, DUAL-GTX1070-O8G
This card costs 406 EUR in Europe, this is the lowest price possible here for this card
The hash rates ranges from 420 to 480, so I picked up somewhere in the middle 450
Power draw ranges from 120 to 140, so I left it at 120 K\W
The results are 2.62$ net profit per day
If we divide 2.62$ by 456 EUR we get 0.0057$ return on each invested EUR
Now lets compare this with AMD RX 580 card:
1) AMD Sapphire RX 580 Nitro Video Card + 8GB
This card costs only 291 EUR here in Europe
The hash rate can get easily stable at 29 MH/s mining ETH
It can also dual mine DCR at 900 MH\s without impacting the hashrate of ETH
This will draw below 130 W, but to be on the safe side I use 130 W
The result is 2.48$ a day (net)
2.48$ divided by 341 EUR initial cost of GPU, will leave us with 0.0073 $ return on each invested EUR
0.0073 - 0.0057 = 0.0016
0.0016 divided by 0.0057 is 21.5% higher return from AMD compared to Nvidia
by the way, if we switch to 13 GPU Mobos we can dramatically reduce the common fixed costs, but as you can see over 20% is still to the side of AMD, which is not little at all
I have been doing such comparisons for the last two months, and i NEVER managed to find an Nvidia card outperforming AMD card, specially if we focus only on the 8GB and above, because anything bellow this could easily become useless within a year, specially the 4GB versions (depending on the currency you mine of course)
Once again, this makes me REALLY very puzzled why would anyone invest on Nvidia cards from PURE financial perspective? I see people building an entire farm of up to 100 1080 TI GPUs, and i wonder if they invested the same amount of money on AMD 580 would they have made more money? All #s indicate that they should make much more on the 580s. So why would someone invest over 100K$ for less ROI?
This makes me feel that i am missing something here
what is it?
