Monday, June 19th 2017

ETH Mining: Lower VRAM GPUs to be Rendered Unprofitable in Time

Hold on to your ETH hats: you will still be able to cash in on the ETH mining craze for a while. However, you should look towards your 3 GB and 4 GB graphics cards with a slight distrust, for reasons that you should know, anyway, since you have surely studied your mining cryptocurrency of choice. Examples are the GTX 1060 3 GB, or one of those shiny new 4 GB RX 480 / RX 580 which are going at ridiculously premium prices right now. And as a side note, don't you love the mechanisms of pricing and demand?

The problem here stems from ETH's own design for its current PoW (Proof of Work) implementation (which is what allows you to mine the currency at all.) In a bid to make ETH mining unwieldy for the specialized silicon that brought Bitcoin difficulty through the roof, ETH implements a large size data set for your GPU to work with as you mine, which is stored in your GPU's memory (through the DAG, which stands for Directed Acyclic Graph). This is one of the essential differences between Bitcoin mining and Ethereum mining, in that Ethereum mining was designed to be memory-intensive, so as to prevent usage of ASICs and other specialized hardware. As a side-note, this also helps (at least theoretically) in ETH's decentralization, which Bitcoin sees more at risk because of the inherent centralization that results from the higher hardware costs associated with its mining.
In time, as the number of blocks in the blockchain increases (at a rate of roughly 14 seconds per block), so does Ethereum's epoch level (which relates to DAG size and the size of the memory footprint your GPU must occupy for its calculation) increase. Every 30,000 blocks, a new epoch emerges, more costly in memory footprint than the previous one. This means that memory requirements for ETH mining are actually increasing as time passes. As the workload's memory footprint increases, it can (and will) overflow from the GPU's memory, and be stored in main system memory. Which, as you know, is much slower to access than the GPU's VRAM (this just made me remember of AMD's SSG graphics solutions. Neat almost solution to this problem, no?) Slower random memory accesses (of which ETH mining is extremely dependent on) will result in performance penalties for your mining hash-rate. And you can see where this is going.
We are currently at epoch #129. Based on current estimates for DAG size and memory requirements, mining with an RX 470 4 GB should yield:
  • Dag 130 - 27.400 Mh/s
  • Dag 140 - 25.100 Mh/s
  • Dag 150 - 22.500 Mh/s
  • Dag 160 - 20.100 Mh/s
  • Dag 199 - 10.000 Mh/s
Currently, an epoch takes about 4 to 5 days to conclude until a new one is started. That means that in around five month's time, a user with an RX 470 4GB will see an almost 30% decrease in hash-rate, with the same power consumption of today. And as you know, in mining, power/performance ratio is all that counts for profitability. It is expected that NVIDIA cards being used currently, such as the GTX 1060 3 GB, will see decreases as well. And there are other performance-affecting details that originate from the increased worker size as well, such as TLB (Translation Lookaside Buffer) trashing, which could see performance degradation even before the memory pool of your graphics card of choice is fully loaded, provided the TLB is itself being overflowed... With Polaris, AMD implemented a TLB cache which was, before, absent from the GCN architecture. The small size of this TLB cache means that Polaris graphics cards will likely see performance penalties from TLB trashing before the DAG size increases to their memory limits. Just another point for you to consider.

Now granted, if you know anything about Ethereum, you probably won't even care about this: the passage from PoW to PoS (Proof of Stake) is expected to occur by November 1st of this year. This means that ETH mining will simply cease to be a thing (though this implementation could see some delays, unlikely as that is.) And it lines up nicely with the 5 month, 30% computing power decrease estimation above. So maybe you don't have to worry that much about ETH mining ceasing to be profitable in 5 month's time. But if you are looking to buy into the mining craze and invest in hardware, you should study this market, and this technology, first (and pay attention to this article as well.) Likewise, if you have just recently bought into the mining hardware market with those exorbitantly-priced RX 400 and RX 500 - do the math and be ready to look for alternatives, either in cryptocurrencies or mining solutions. Don't let yourself be burned just because you want to follow the train. Sources: Cryptomining-blog, Bitcointalk, Ethereum @ Stackexchange, r/Ethermining, Bitcoinmagazine.com
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28 Comments on ETH Mining: Lower VRAM GPUs to be Rendered Unprofitable in Time

#1
Ferrum Master
Good... I need a cheap card for my LP box...

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#2
Chaitanya
So does this mean soon the SKUs with 4GB or lower RAM will be left alone by miners? current shortage of GPUs is quite irritating.
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#3
KainXS
It looks like the 8Gb RX 480 also drops at higher dag and if ethereum really does move to proof of stake will it even matter anyway, probably not.
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#4
meirb111
to me all this mining smells and feels like a scam ,but that's just me.
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#6
atomicus
StefanM said:
You are not alone...
http://www.cnbc.com/2014/03/14/buffett-blasts-bitcoin-as-mirage-stay-away.html
LOL, you realise what Bitcoin was valued at when he said that (in 2014), and what it's worth TODAY?? Just over $400 vs just under $3000!! Whether he turns out to be right in the long term or not, in the short term he called that COMPLETELY WRONG!! I was going to buy a few coins myself when it was about $200 back in 2013. I listened to all the naysayers and doomsday talk that it was about to collapse and be worthless, and I also recall the ridicule some people got for suggesting it would ever reach a 4-figure value. The only truth is that NO ONE KNOWS!!!
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#7
xkm1948
I do wonder whether RAM speed has any effect on this.
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#9
toilet pepper
xkm1948 said:
I do wonder whether RAM speed has any effect on this.
Yep it does.

Looks like 1070s will become a lot more expensive as well.
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#10
Ubersonic
This isn't a VRAM size issue it's a VRAM access issue, hence why it's also affecting the 8GB Polaris cards but not the 4GB Hawaii cards (In addition it also reportedly affects the GTX970 but not the GTX980).
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#11
ppn
if I get a free GTX 1170 in 5 months for just having my 1050 Ti 14Mh burn 50 watts at 70% power, thats fine. but now i want 2 1170's and then 4. whats wrong. i need them solar panels on roof asap
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#12
xkm1948
Strange. So technically it should not affect Fury line up as well. Nano would be perfect for mining then. Low heat and yet full speed HBM.
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#13
figuretti
It's not like the Polaris cards can't be used to mine other crypto... probably the people who invested in this short period of time will sell againt their cards, but the old miners, the more experienced... who will stay in the game for much longer... they'll continue to mine every crypto they can... Jesus, they're still mining other crypto with the 280X, even if you can't mine ethereum since the DAG's of nov'16...
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#14
xkm1948
Asked around some mining community. Well it is definitely NOT VRAM size limited, but total throughput bound.

So HBM based Fury/Nano with 512GB/s throughput will be the last consumer GPUs along with TitanXp to be affected by the hash-rate drop problem
In short, this is actually very good for Fury/Nano, as miners will start to scrap up those older cards as well.
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#15
Captain_Tom
Anyone who invested in this should have done the math.

With the deals I got cobbling together my rig, I calculated that it would pay for itself in under 2 months, and so the PoS switch was no problem.

That gives me 3 months worth of VERY nice profit, and then I will just set it to ETC or Siacoin and let the thing have fun for a year!



Anyone buying these cards at $400 is idiotic though, unless they got the rest of the components for free or have some other masterplan.
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#16
R-T-B
Chaitanya said:
So does this mean soon the SKUs with 4GB or lower RAM will be left alone by miners? current shortage of GPUs is quite irritating.
largely, yes. There are still other coins they could mine but many won't bother.

xkm1948 said:
Asked around some mining community. Well it is definitely NOT VRAM size limited, but total throughput bound.

So HBM based Fury/Nano with 512GB/s throughput will be the last consumer GPUs along with TitanXp to be affected by the hash-rate drop problem
In short, this is actually very good for Fury/Nano, as miners will start to scrap up those older cards as well.
Etherium mining is vram limited (or will be soon). I'm unsure who you talked to, but they were wrong.
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#17
hat
Enthusiast
Well, I invested almost $900 (on credit) in two GTX1070s. The plan is to recoup my investment, and once I'm running in the black, use the earnings to pay down other debts freeing me of some financial burden, while investing more in mining. Two more cards, new board, ram, cpu, power supply and case for my second rig. Essentially an all new system. But that will come only from mining earnings.

I never thought I'd be upgrading PC hardware anytime soon, but I'm taking the chance to earn some money with it, after I return my investment.
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#18
R-T-B
hat said:
Well, I invested almost $900 (on credit) in two GTX1070s. The plan is to recoup my investment, and once I'm running in the black, use the earnings to pay down other debts freeing me of some financial burden, while investing more in mining. Two more cards, new board, ram, cpu, power supply and case for my second rig. Essentially an all new system. But that will come only from mining earnings.

I never thought I'd be upgrading PC hardware anytime soon, but I'm taking the chance to earn some money with it, after I return my investment.
Bold.

I hope the market stays stable for you that long man.

toilet pepper said:
Yep it does.

Looks like 1070s will become a lot more expensive as well.
Ram speed only has an impact if the GPU memory overflows I think.

Ubersonic said:
This isn't a VRAM size issue it's a VRAM access issue, hence why it's also affecting the 8GB Polaris cards but not the 4GB Hawaii cards (In addition it also reportedly affects the GTX970 but not the GTX980).
Ok, this is news to me, but I might be completely off on how Ethereum operates.

Does anyone have some links on this?
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#19
Supercrit
xkm1948 said:
I do wonder whether RAM speed has any effect on this.
It's more memory bandwidth limited than size. Hawaii cards have 512bit memory, it largely compensated the slower VRAM speeds, and at stock speed the memory is bandwidth is still not saturated right now. OCing the VRAM on Hawaii cards currently does nothing but it speeds up these 256bit Polaris cards since they are memory bandwidth starved.
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#20
Raevenlord
News Editor
R-T-B said:
Ok, this is news to me, but I might be completely off on how Ethereum operates.

Does anyone have some links on this?
The article explains, and there are some very relevant links in the source.

There are two issues. One with worker size, where the DAG will increase in size with each new epoch (the number of finished blocks by 30,000 intervals) until it is over the physical memory present in the cards (3 GB, 6 GB, 8 GB...) This Is happening, and is intrinsic to the way PoW is designed in Ethereum. It's mathematic.

The other issue, which is being referred to and which is in the article as well, is Polaris' implementation of a TLB cache. The Polaris implementation is small, and is already showing signs of overflow with current DAG sizes. So even though physical VRAM limit isn't reached yet on 4, 8 GB Polaris, the TLB cache is being pushed to its limit with regards to the size of the virtual address (as well as the abundance of random read orders which ETH mining demands from memory and the TLB cache.) This results in read misses for the TLB cache which forces it to be refreshed, which is very costly in Polaris.

Previous AMD GCN didn't have TLB cache, hence why they aren't affected BY THE TLB CACHE MISSES (just Google AMD GCN TLB CACHE and look at the GCN white paper. They explicitly say GCN does not need a TLB cache.) However, these cards will still be hit by the worker size exceeding 4 GB problem, IF ETH doesn't implement PoS before the DAG size increases to that value. If it does, the point is moot, DAG won't ever achieve 4 GB sizes, and users can mine other coins happily.

Hope this clears some stuff up. There is only so much one can say in an article before the TL;DR drama.
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#21
R-T-B
Raevenlord said:
Hopened this clears some stuff up. There is only so much one can say in an article before the TL;DR drama.
No worries, it was my fault for attempting to read from a painfully outdated cellphone. I'm home now and will read it to completion after I do my news run of coverage. :D
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#22
ppn
Epoch just moved to #130
2375 MB currently used. Mh/s about the same.
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#23
cdawall
where the hell are my stars
It just means people mining ethereum will migrate to zcash, vertcoin and LBRY. All of those are still profitable on lower vram cards.

Also I did not see a drop with the new Epoch on my 1060 3GB cards.
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#24
YukikazeQ
xkm1948 said:
Asked around some mining community. Well it is definitely NOT VRAM size limited, but total throughput bound.

So HBM based Fury/Nano with 512GB/s throughput will be the last consumer GPUs along with TitanXp to be affected by the hash-rate drop problem
In short, this is actually very good for Fury/Nano, as miners will start to scrap up those older cards as well.
fiji is pretty poor at mining eth in general from what I've seen with mods to memory timing to get more bandwidth on a 480/580 you can get higher hash rates than any fiji card lol
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#25
cdawall
where the hell are my stars
YukikazeQ said:
fiji is pretty poor at mining eth in general from what I've seen with mods to memory timing to get more bandwidth on a 480/580 you can get higher hash rates than any fiji card lol
To be fair you can normally beat Fiji with a 390x
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