Topic: Mining with 2 GPUs (Read 200 times)

https://forum.ethereum.org/discussion/9277/1080-specific-ethereum-mining-issues   This explains it a little bit and from my understanding its something to do with latency.  most of the articles you read will be talking about the 1080 and ethereum, but this applies to any memory intensive algo.  For example, if I am mining Neoscrypt, the hashrates of my 1070s are higher than my 1080s.  In other algorithms the 1080s are higher, but really there is only downsides to the 1080 since it limits you somewhat with the coins you mine.

Thanks a lot for the detailed post!

Indeed I was wondering about the noise generated since the majority of the cards recommended have 2 or 3 fans per GPU. Good point with the water cooling.

Interesting thing with the difference between GDDR5X  & GDDR5 I didn't expect older technology to be better for mining. Need to read more about it.

So I have a good frame of reference, as when I started mining I built a machine from scratch with 2 GPUs.  I wasn't building it for gaming, but I had this computer in my bedroom and planned to use it as my PC so I didn't buy the cheaper or bare bones components that you can get away with with a true dedicated mining rig.  In hindsight I would have done a couple of things differently but I think I did pretty well for being a newbie (with mining, not computers).  So here is what I started out with (this was built July 2017):

1. Asus Prime Z270A - $120.  Can run 8 GPUs
2. Refrubished Corsair Axi 860i platinum - $100.  Hooks into your motherboard to report power consumption.  Good feature for me at first considering I didn't know what to expect on power usage
3. I5-7500 - $200
4. Corsair Carbide Air 740 case - $130 - http://www.corsair.com/en-us/carbide-series-740-high-airflow-atx-cube-case
5. Corsair 16 GB RAM - $120
6. - 2 EVGA GeForce GTX 1080 08G-P4-6286-RX FTWs - $900
7.  Samsung 500 GB Sata SSD - $150

Once I got that running I also added in a GTX 1060 3 GB for $200.

Additionally, the fans of the cards would get so damn loud and it was so hot that I could barely sleep.  I bought 2 watercoolers for the EVGA cards at $120 each.  This made the rig extremely silent.

Total cost:  $2060.  Not bad for a rig that would do decent gaming and mining.

And since then I've sold the 1060, bought 2 1070s and a 1050ti.  3 of the cards are in the case, 2 are on risers in a shoebox behind it.

Now for a few things I found out the hard way:

1.  When I started this venture, I did it to mine ETH.  I didn't really find out about other cryptos until I realized how shitty the gtx 1080 is at mining ETH.  Like it is worse than the 1070.  The GDDR5X memory that the 1080 and 1080ti come with are terrible with mining memory intensive coins.  I've done lots of reading on it and still have never found a straight answer as to why this memory is so great for games but bad for mining.  The gtx1080ti can skirt around this a little bit though because it has such massive memory bandwidth. And this lesson leads me to the next:

2.  Mining 2 currencies at once is for the birds.  I had my 2 1080s mining LBRY, and my 1060 mining ETH.  When other coins would become more profitable, then I would switch, but it is a giant hassle having to calculate profitability on 2 different coins for your multiple cards. It also makes it difficult to use algo switching miners because they will only launch one miner at a time.  And not to mention different overclock settings to manage.

3.  Recently I ended up buying an I7-7700K on ebay.  I realized I was missing out by not also mining a cpu coin while my GPUS were at work.  Cryptonight mining is based on your L3 cache.  the I5 only has 6 MB, the I7 has 8 plus hyperthreading.



So to wrap this long winded post up, the main things I think that are crucial for the set up you want:

1.  1000+ Watt power supply.  After 860w they seem to get quite a bit more expensive, but I think this is the best way to future-proof.  Right now my rig is maxed out, not because of the 8 slots that I can plug cards into, but because my power supply is already at capacity.  I know you only want 2 cards, but I am guessing you will end up with more eventually

2.  A case with at least 8 expansion slots.  The most typical number is 7, but trust me, get one with 8

3.  A motherboard with 4 PCIE x16 slots.  While my board can accommodate 8 cards with risers plugged into the 1x slots, it only has 3 x16 slots which means I can really only plug 3 cards directly into the board.  Again, I know you only want 2 cards now, but if you want to expand, it would be nice to have the ability to put in 2 more cards without any hassle.

4.  Processor with 8+ MB L3 Cache.  This will increase your game performance, and also net you over a dollar a day mining a cryptonight coin.


As for CPUs, the Ryzens are going to be your best bet.  The one caveat though is that the motherboards for them are expensive, so its almost more expensive than buying intel.  For this reason alone I would recommend an intel board with a Z chipset and an i7 processor.  The new ones especially since they have more cores and higher L3 cache.


For cards, there is no doubt that the GTX 1080ti is king.  Of course they are also $700 each.  If money is a problem, but not a huge problem, I think that you can't go wrong with 2 gtx 1070tis.  Their performance is close to the gtx 1080 and they don't have GDDR5X memory.  Not to mention if you have 2 identical cards you can put them into SLI for gaming.

Embracing the speculative aspect of mining is important for any new miner. If you want to diversify and mine multiple coins without having to constantly trade, then having one of each may be beneficial. (But be sure to make note of which mining algorithms are in play, since, for example, Nvidia GPUs tend to be better options for equihash, and AMD GPUs tend to be better for cryptonight.) However, either option gives you a fair amount of options for mining. (Definitely more flexible than ASICs.)

For GPU performance, rely on reported hashrates for a given card on various algorithms. The amount of graphics RAM is important for ethash coins, since the growing DAG size increases memory requirements to mine. (Currently 2GB cards are obsolete.) 3GB cards aren't that future-proof, but usually ethash coins aren't good options for them anyways. (The most recent 3GB card, the GTX 1060s, shine on equihash far more than ethash, and the old 3GB 7950s aren't great for mining on ethash either.)

For CPU mining, also look for reported information, although it may be harder to find.

As far as system RAM goes, when mining, you only need enough to run the OS and mining software. 4GB is usually a safe bet.

Is the calculator of nicehash accurate?

I looked over https://www.nicehash.com/profitability-calculator and it seemed like some algos are better covered by amd and other better by nvidia.
Another reason why I thought about this approach was in case some other altcoin is developed and works best on the other vendor so I could have better coverage and not risk being stuck on an altcoin that increases
difficulty and end up not making anything in return.

Do you guys see any advantages in using 1 nvidia & 1 amd gpu in one system or everything is negligible?

When it comes to GPU performances what is more important for mining? bitrate? memory size? frequency?
I've read that ETH is using DAG that increase overtime and this would need more than 2-3 GB.

When it comes to the CPU what is more important for mining? higher L1/L2 cache levels ? CPU frequency?

Also, does RAM play a role in mining? What ram types are better?

Thanks for the tips! Yes, that's what I was thinking about - having the CPU mine other coins in the mean time or have it working fine for gaming as well.



Thanks for the tips!
So, basically when you say "Claymore's Cryptonote (XMR/ETN) is only AMD" that would mean the mining software would not detect the nvidia GPU, right?
I suppose I could use another mining app designed for nvidia and that should work fine at the same time with the other app for amd, right?
Although the disadvantage would be you cannot mine with both GPUs to increase the hash rate.



Thanks for the tips!
1. I didn't select the OS yet, I'm a windows user but if hashing is better on Linux (although I haven't heard of something like this yet in the few days I've researched this) I would consider moving and solving the headaches. I have a computer science background, I should be ok.
2. Yes, w/h = "watts per hour" sorry for the ambiguity.
3. I was thinking of also using the CPU for mining and in case it's not working out, I could sell it/use it as a gaming PC.
Yes, you are correct, gaming also requires other components but I was thinking to use a 250 GB SSD, 8-16 GB RAM & a decent CPU that can also mine/run games.

If you want a decent gaming PC, you'd better have a clear vision of what you're expecting, since that will place constraints on at least one of your cards, your CPU choice, and other components.

1. You can mix AMD and Nvidia GPUs fairly easily on Windows. Most Linux distributions tend to make mixing them much more of a headache, but it is possible.

2. This depends on the exact components selected. Also note that the typical unit for power is watts (joules per second), not w/h.

3. This depends on your goals for the rig as a gaming system. For most users, an i3 or i5 will suffice. Alternatively, you could go with an AMD-based build. (Pay close attention to the chipset if you are thinking about expanding the rig.)


Note that this rig might not pay for itself. Making a mining rig also work effectively for gaming (depending on user expectations for gaming performance) usually requires additional RAM, storage, a more expensive CPU, etc.
This rig only has 2 GPUs, one of which will be mining part-time. You'd be tasking 2 cards with the burden of paying back not only their initial cost, but also that of the rest of the rig. (This is one reason why rigs with more GPUs are favored, as mining with more GPUs and/or more powerful GPUs makes better use of the overhead cost associated with purchasing and powering the rig base {motherboard/CPU/RAM/etc.}, which does not directly contribute to revenue.)

Of course, you might end up with a nicely "discounted" gaming rig.

Totally agree... mix and matching AMD/Nvidia is not trivial as depending on what miners you use it might not be so easy
For instance Claymore's Ethereum mining would work on both Nvidia & AMD however its Cryptonote (XMR/ETN) is only AMD, you need a separate software for Nvidia
I would recommend trying to get 2 AMD RX 580 it's more profitable than the GTX 1060 however not by much (for the past few months atleast)

It's possible to mix AMD and Nvidia cards on the same mobo, but it tends to be temperamental and not really advisable for the noob miner.

I have a dual GTX 1060 3GB rig mining ZEN that delivers about 610 H/s on average and uses a total of 315W at the wall (the entire system). Cards are set for 85% power limit and modestly overclocked to 2000/4150.

If you mine a Cryptonote coin like Monero, Electroneum, etc., then a powerful CPU can easily pull its weight. The Ryzen 5 1600 I have in one desktop does 370 H/s while an older FX-8300 still delivers a respectable 190 H/s; a really ancient Phenom II 955, however, only manages 55 H/s and Windows (7) slows to a crawl.

So a possible setup would be two RX 570 or GTX 1060 plus a decent CPU so you can use a GPU miner program at the same time as a CPU Cryptonote miner (e.g. - Claymore's v3.9).

I'm thinking of building a mining/gaming PC with 2 GPUs and was thinking which setup would be best to cover the majority of algorithms (non-SHA-256 related)/altcoins with decent speeds.


1. Have you guys tried to mix nvidia (e.g. GTX 1060 6gb) & amd (e.g. RX 470 4gb ) on the same motherboard? Does this help in covering more algorithms with better speeds?
2. Any idea on the power consumption of the whole system? I've seen posts about these cards under volted @ 110 - 150w, so would 4-500w/h be a good approximation of the wall consumption for the whole system?
3. Would investing in a good CPU also be a good idea? If so what do you recommend?


P.S. I'm more interested in treating this as an investment (mining coins and keeping them/exchanging for others not selling them asap).