Great question - and before I answer I’d just like to say that what I write here is the result of my own experiences, limited as they may be. I’m not suggesting that anyone else should change what they are doing or that this is the best possible solution. I’m putting this information out there for others to look at and decide what it is that they might want to do - so I’d appreciate not being attacked for doing so.
I’d also like to say that in my numbers below, I have assumed that the rig (mobo, cpu, SSD, etc) in which these cards are going to operate will consume a consistent amount of power when running, regardless of the cards you are using - therefore I will ignore the “power at the wall” numbers and just use the power consumption of the different GPUs in order to compare them.
Right - I’d probably put together a home mining rig based on the cheapest RX570 8Gb card that I could get. Each one of these will mine the Ethash algos at about 31mH/s and use about 85W per card doing so (I have uploaded pics of my rigs achieving exactly this). That is an efficiency of 0.36mH/W.
I also have a rig that runs 6 x RX5700 (non-XT) GPUs and these are achieving 52mH/s and using 75W (pics also uploaded on other threads). This is an efficiency level of 0.69mH/W.
Efficiency is a simple way to compare the likely return for cards with different hash rates and power consumptions. It shows how much hashing power your rig submits to the pool for each Watt of energy that you expend. In simple terms, the more hashes the more money you will make per unit of energy.
On the surface, the 5700 has almost twice the hashing power per Watt so would seem to be a better option - but there is always a catch. Where I come from, they are very popular and therefore cost more than twice as much to buy one. The cheapest 5700 that I can find delivered to my place is about $464USD. The cheapest 570 that I can get delivered will cost me just $168USD. You could substitute your local prices in the calculations below to see if it holds up in your area.
So when I compare the efficiencies of the 2 cards having allowed for the cost I get the following:
RX5700 - for every dollar I spend I will get 1,487H/W (690,000H/W / $464)
RX570 - for every dollar I spend I will get 2,143H/W (360,000H/W / $168)
This could be explained another way by asking “what efficiency do I get for each $464 I spend”. The RX5700 is of course 0.69mH/W as shown above. For $464, I can buy 2.76 RX570s so simple maths tells me that the efficiency I will achieve from this purchase is 0.99mH/W.
So on an Efficiency per Dollar comparison, the RX570 gives me a better outcome. In fact by this measure, it is 43.5% better value for money.
In addition, the RX5700 requires an 8pin and a 6pin PCI-E connector into each card while the RX570 only requires one 8pin connector, leaving the other 6pin PCI-E connector free to power your PCI-E Risers. Powering the Risers on a 5700 rig can either require you to use (what I have found to be) the less safe/reliable SATA or Molex connectors if you don’t have any more PCI-E connectors, or spend more on your PSU to make sure you have enough connectors.
Now for the caveats.
I only use AMD and I only mine Ethash with them because (in my experience) I have never seen any algo that comes close to the profitability of Ethash and I have never seen any Nvidia cards that come close to AMD for mining Ethash (this can be seen from the whattomine.com website as well). I have a Nvidia 2080 Super (water cooled) and it doesn’t even hash as fast as my 570s while costing about 7 times as much to buy and using twice the power. Admittedly, I haven’t spent any time trying to tweak it and I might get better results if I did, but really what’s the point, it’s never going to improve enough to threaten the 570s on a value for money measure.
My 570s have been BIOS modded to RX580 BIOS (a job that takes less than 5 minutes per card) so they probably get a couple of mH/S more than one straight out of the box. If anyone is interested, I could write you a guide to the modding that would be shorter than this post!!!
Finally, I’ve never had any experience with Radeon VII cards - they are way too expensive here where I come from so I’d be interested to see numbers from anyone who is using them.
What else is out there that we should look at? I’m about ready to build another rig and open to considering options if the numbers stack up.
. It really isn’t any riskier than modding a 570. I have modded all of mine at least three times before deciding on the right settings and have had no issues with the process so far.