Teachings from a Frankenstein Mining Rig

Stuff happens and let's say you end up with a couple of different cards in a single rig. Perhaps you couldn't pass up a couple of 2nd hand offers, you had to replace some cards.. anything. Is this trouble or opportunity?

The challenge then is to get each card to do what it's best at... and so if you are choosing cards for a new rig, or trying to optimise what you have - there might be something below that can help you make more fruitful decisions.

I was faced with a multi-card short time ago and it turned out better than expected. My original plan was to just to mine ETH with NVidia 1060's. Except one card didn't work, was send back for replacement, and one 1060 was an MSI gaming X+ which is much slower than my other 1060's for ETH.

My 'frankenstein' rig composition:

• 5 x MSI Gaming 3Gb (samsung memory)
• 1 x MSI Gaming 6Gb (micron memory)
• 1 x MSI Gaming X+ 6Gb (very high latency memory - 20% slower than the above in ETH)
• 1 x EVGA 1080 SC (generally known to have poor memory for ETH)

Finding out what each card is best at

My first plan of attack was to find out what each card is best at. Using whattomine.com, measuring power draw and a speadsheet, it turns out the 1080 is spectacular at mining Groestl. Even when taking in account power consumption and its purchase price (not much more than a 1070 now), it beats any other card. However no 'Groestl' based coin is worth anything meaningful as of today. So it was now clear to me that I also needed to get the price of the coin into it.

In the end, I put all factors together: purchase price, cost of the rest of the rig, power consumption, hash rate for a currency, the expected rewards and the value of the coin mined. Here's what that looks like for me being in NSW, Australia:

The number of months to break even assuming a re-sell at 50% of the purchase value.

While the actual earn back period fluctuates a lot with currency prices and hardware prices, these earn-back periods hold up pretty well relative to another card.

The right job for the 1060's and the 1080
So using this data, the normal Gaming X's are going to work on ETH. Mine get about a 23.5 - 24.8 hashrate at 0.8V (67-73W per card).
The 1080 is clearly destined to mine ZCash right now (485Sols at 0.8V / 120W).

The best job for the 1060 Gaming X+ / any 1060 card with poor memory OC
And finally the 1060 Gaming X+.. it really should have gotten it's own 'graphics cards' column; it's memory latency causes it to be a lot slower for ETH.

What 1060 performance depends on
Why slower? Well ETH on the 1060 is completely held back by the memory speed. Having 9 computes in the 3Gb version is exactly as quick as the 6Gb version with 10 compute cores. However when optimising 1060's for ZCASH... memory speed has nearly no influence and processing power is everything. To sum it up: for Equihash, you can use the worst memory overclockers, while for ZCASH you want those with the best core clocks.

Typical ETH 1060 tweaks:

• memory: +900 for samsung, or +720 for micron memory
• core: 1400Mhz @ 0.8V

Typical ZCASH 1060 tweaks:

• memory: +0
• core: 1725Mhz @ 0.8V

In conclusion

A mining rig with several cards is a bit more complex than having one type. When mixing AMD and NVidia you could run into issues as well. You'll certainly will need to optimise each type of card for the currency that it will be best for. If you are mining under Windows, I'd recommend to keep a couple of profiles in afterburner ready for each miner, so you can easily switch as the values of coins change.

On the plus side, having a couple of cards, can make you a bit more versatile in taking advantage of changing market conditions, even if sometimes not all cards are dedicated to the most profitable currrency. You will also gain a lot of insight in cards and what to buy next.

Note also that in the end, everything depends on prices in your particular country, area or electricity plan even. Cheaper power will make the RX570 better at ETH than a 1060 at some point, while a 1060 or a 1080 is potentially a more versatile card doing more coins pretty well.

In any case: Happy mining and until the next time.
Crypto Ed