Posts Tagged ‘GPU mining

While AsRock has not yet released for sale their new motherboard AsRock H110 Pro BTC+ With 13 GPU support we already got confirmation that it is working with 13 video cards for mining under Linux and Windows. The sale of the new Pro BTC+ mining motherboard will probably not start before next month, but we already hope to be able to get an in-depth review hopefully by the end of this month or early next month.

Running 13 GPUs on a single mining rig might be a bit of a challenge as it is not only the motherboard that needs to provide you with the base, but you also need to take care of other hardware as well. Hardware such as power supplies that will handle 13 GPUs, we are talking about multiple PSUs for sure. There are also other possible challenges associated with more GPUs such as higher requirement towards the memory/swap as well as maybe even faster CPU to handle additional load coming from the mining software.

We have seen proof of 13 AMD GPUs running on the AsRock H110 Pro BTC+ motherboard under Linux using the ethOS distribution for mining as well as 13 Nvidia GPUs recognized and working under Windows 10. We are yet to confirm this ourselves by testing the motherboard, but what we are seeing as results already is reassuring that we are going to get a real and working solution for more GPUs per mining rig than what is currently available in terms of 6, 7 and even 8 GPU mining motherboards. Since the AsRock H110 Pro BTC+ motherboard is designed with crypto mining in mind it should be easy and problem free to setup, unlike some other motherboards that people are using at the moment that need some special settings or tweaks in order to make them work with more video cards than they are originally designed for.

We are getting reports for a new trend that is peaking up recently with all of the shortages with hardware due to the boom in mining. It seems that some retailers will happily sell you their stock of GPUs and will then tell you that they will not give you any warranty or accept RMA in case of a problem if you are going to be using the video cards for mining. At the same time they are happily willing to sell you not only the GPUs, but all other hardware that you may need to build a mining rig. The problem here is that instead of clearly pointing that they will not hold any warranty for products used for mining, they take your money, ship you the goods and then inform you that there will be no warranty if the hardware is used for mining. This is just not the correct way of doing business… though it is hard to confirm what a GPU was actually used for anyway, it sounds more like a threat to the customer than something that can be truly enforced.

The main concerns with hardware used for mining are regarding the GPUs working under heavy load 24/7. This makes them prone to more issues as they hold higher operating temperatures, fans are more susceptible to failure (especially if not good quality ones) and as a result the cards can fail. Base on our experience however if properly cooled and maintained the fact that a good GPU is used for mining instead of occasional gaming is not really a problem. Most of the GPU failures usually happen in the first few days and are often caused by some small defect that is prone to result in an issue sooner or later anyway. All in all it is important that miners take a proper care of their mining hardware in order to ensure its long and reliable operation and if they do it good enough, then the trouble they will have are going to much less than if they don’t…

The problem is that there are a lot of people that are getting into mining that do not care about anything, they just throw a bunch of video cards somewhere and start mining and when there is a problem they just RMA them. They do not care about proper cooling, optimizing settings for efficiency or performance or anything else, they just want to mine and make profit from as easy and as fast as they can. We know for a fact that one of the most common RMA reasons are failed fans of video cards that are under warranty, again here some vendors are to blame as they are putting cheaper and lower quality fans. If you have good dual ball-bearing fans that are well protected from dust and do not have an issue with increased temperature you are much less likely to get into trouble. We are however still seeing cheap fans with bushings instead of ball bearings and not very tolerant to higher operating temperatures being widely used on not so cheap GPUs.

This brings us to the 3 month warranty that Nivida is planning to offer for their GeForce GTX 1060 9Gbps based mining GPU. It seems that they are also worried that a longer warranty might not be cost effective for products dedicated for mining, but then again it also shows that they may not be that ready for properly making mining GPUs… just more cost effective solutions. On the other hand if you look at the warranty that ASIC miners do come with limited warranty. For example the Bitmain Antminer S9 ASIC miner does come with a 180-day warranty starting from the date the unit is shipped to you. Baikalminer has just a 30-day warranty for miners. In general the warranty you get for dedicated mining hardware may vary from none to up to about 6 months period. However this is clearly stated before you buy the product, and not you getting a nice and not so pleasant surprise after you pay for it and get it shipped to you for example.

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It seems that still a lot of people may overlook the importance of the power supply when building a multi-GPU mining rig and the more the number of video cards, the more the issues may arise. Normally people think that if you have six video cards with a TDP of 150W, then any decent 1000W power supply should be just fine for the job in providing enough power for the mining rig. Doing the simple math it will, however when we get to actually connecting everything things may actually start to get messy. You might discover that you have not properly planned the number of power connectors you need for the video cards that you need, or the number of 4-pin Molex connectors needed for the powered risers. The simplest solution here would be to just add some splitter adapters and got a few extra connectors available to be able to just connect everything. Unfortunately the simplest solution here is definitely not the wisest thing to do as you might end up overloading some of the wires going to the PSU…

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The first thing you need to ensure is that the power supply you go for has enough PCI-E power connectors available to power all of your video cards in the mining rig. So if you have 6 video cards getting six separate PCI-E power connectors from the power supply is the best solution. Unfortunately not many power supplies are designed with single cables for 6 or even more PCI-E power cables as normal computers rarely have more than 2 or up to 4 video cards in rare cases. Even if a power supply has let us say 8 power connectors these are usually double connectors going from a single wire to the PSU and this is originally designed for up to 4 video cards (if they have double PCI-E power connectors). Adding additional adapters splitting single PCI-E power connector to dual PCI-E or using Molex to PCI-E power adapter can cause problems, so if possible it is wise to try and avoid it. If not, then you at least need to make sure that you are not overloading any of the lines going to the power supply, the easiest thing to check for that is to touch the cables and if they are getting hot, then it is not Ok.

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If you are using a motherboard with multiple PCI-E slots like the AsRock H81 Pro BTC motherboard that is actually designed to be sued for GPU mining rigs you will need to use extenders. Although the motherboard has extra 4-pin Molex power connectors in order to properly power video cards that need more power from the PCI-E slot. Even in this case it is still better to go for powered PCI-E risers and do not try to draw more power through the motherboard, especially if you go for 6 GPUs. The x16 PCI-E slot that is normally being used for video cards on the motherboard is designed to provide up to 75W of power to the video card by specifications, though most of the consumption comes from the 12V line and there the max power is rated at up to 66W. If you however have 6 video cards that are maxing out the power draw from the motherboard it will come up to a pretty high number, even though in most cases video cards do not go with the maximum power that the PCI-E slot can provide them with.

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There are a number of different PCI-E risers, but one that is very popular choice is the x1 PCI-E to USB 3.0 riser as it is really well designed and works very good, unlike the case with not so well made ribbon cable extenders. These risers use a USB 3.0 cable, but they are not actually using USB interface, the cable is just a good choice for the data communication without issues. PCI-E risers like the one on the photo rely on 4-pin Molex power connector to supply any power that the video card may need, completely cutting any power draw from the motherboard’s PCI-E slot. We already know that the video card can draw up to 66W over the 12V line and this should normally not be a problem for a 4-pin Molex connector as these connectors are rated at 10-11A per wire and since there is just one 12V wire you should in theory be able to go for up to 120-132W over it, but that is only if you have a single Molex power connector.

The actual problem with 4-pin Molex power connectors are not the connectors themselves, but the cables that are being used to route them to the PSU, because they also have a maximum power rating depending on their thickness. Power supply manufacturers and cable adapter manufacturers do not go for the best option as it would make things more expensive and in most cases it will not hurt to go for a thinner cable. To be able to get up to 10A current over a 4-pin Molex connector you would require a 14 AWG or 16 AWG wire, 18 AWG ones are rated at up to 8 Amps and 22 AWG wires are rated for up to 6 Amps. Unfortunately most manufacturers do not go for 16 AWG let alone for 14 AWG wires on Molex connectors (usually 16 AWG wires used on PCI-E power connectors on high-end power supplies). In most cases the power supply wires for the 4-pin Molex connectors are 18 AWG, though there are cases, especially for adapters or extenders where even cheaper 22 AWG wires are being used.

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If the maximum power draw for a video card over the 12V line of a PCI-E slot is 5.5A (66W) then even a 22 AWG wire rated at 6 Amps should be enough. It should, but only if you connect only one such 4-pin Molex power connector to a line going to the power supply. That is rarely the case however as power supplies normally have a couple such 4-pin Molex connectors on single line going to the power supply and that goes over a 18 AWG wires. In order to be safe a maximum two PCI-E extenders should be powered by such cables to stay within specs or at least close to them, but people often use three or even four of these connected and that can lead to cables overheating and melting or even burning and damaging your expensive mining hardware as a result.

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Normally with video cards that have external PCI-E power connector the maximum of 66W over the PCI-E slot is never reached, it will be more like up to 30-40W for example (or less), though there are exceptions as well – the reference design Radeon RX 480 GPUs. Even at 40W if you connect three or four of the 4-pin Molex power connectors that use a single cable line to the power supply, then you will still be over the maximum rating of the cables. What happens is the cables starting to heat up and as a result they may even melt and short out and that can do things like start a fire, damage your video cards, motherboard or power supply etc.

The easiest way to discover such a problem is to just touch the power cables a few minutes after you have the mining rig up and mining, so that it is under heavy load and using a lot of power. Cables that are hotter to the touch than the others are probably near or over their limit and you should think of a way to reduce the power draw over the specific power line to the PSU. If you have a thermal camera you can just take an image like the one above and see the problem clearly and diagnose which cable might be overloaded and do something about it. But even if you don’t have extra tools to assist you, even just touching and noticing a hotter cable can be enough to find an issue with the power distribution of your mining rig. Do not overlook possible issues like that as later on they may cause you serious headaches and even cost you a significant amount of money, taking you on the red, instead of you actually making profit from mining.


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