All About BTC, LTC, ETH mining as well as other alternative crypto currencies
When looking for the best settings for GPUs that will be used for crypto currency mining it is often considered a good practice to optimize them for better efficiency and not for maximum performance. Going for the maximum performance often results is overclocking and thus higher power usage for the extra few hashes, not to mention the additional heat and as a result the overall efficiency may not be as good. If you are looking for the optimal efficiency you will most likely try to reduce the power usage of the GPU to decrease the power usage and heat output and not sacrifice any or at the cost of just a little performance drop. This is exactly what we are going to be doing now with the recently announced Nvidia GeForce GTX 1080 Ti Founders Edition video card, trying to find the sweet spot in terms of efficient (best hashrate per Watt of power used)…
For the purpose of our tests we are using the latest NiceHash Excavator v1.1.4a miner running on the Equihash algorithm used by Zcash (ZEC). Do note that other algorithms may need different settings for reaching better efficiency than the one tested here. Currently the Equihash algorithm is among the most profitable to mine on Nvidia CUDA GPUs, so we are focusing on it. Since all recent GPUs from Nvidia have both a base operating frequency and a boost operating frequency and the video card is managing the optimal one based on factors such as TDP and temperature it is easy to look for better efficiency just by lowering the TDP limit. This will essentially result in lowering the maximum boost frequency of the GPU and is an easy and very good thing to start from, if you wan to dig deeper you may also try to lower the operating voltage of the GPU in order to further improve the efficiency by lowering the power usage.
In the table above we start with the GTX 1080 Ti running at the maximum TDP level that is allowed with the +20% increase of the Power Limit meaning 250W default TDP + 50W increase or a total of 300W allowed. At this maximum allowed level you cannot expect to be anywhere near the optimum efficiency, not to mention that the GPU may not be able to reach that power usage anyway without further overclocking. We are however going to stay at the default settings and not overclock, playing only with the boost frequency of the GPU by lowering the TDP. The final result showed that the optimum efficiency in terms of hashrate per Watt is with around 60% TDP or about 150W for the GTX 1080 Ti… that is for the Equihash algorithm used by Zcash (ZEC). With that setting the operating frequency of the GPU stays at just a bit shy of 1500 MHz, or to be more precise at the 1480 MHz base operating frequency. What essentially this means is that while the extra Boost frequency may rise the performance you get, the more it scales up, the less efficient the GPU becomes in terms of performance per Watt of power used. No wonder Nvidia has chosen this particular operating frequency as the base one for the GTX 1080 Ti, and the GPU manages to keep it up with a TDP of just 150W for mining the Equihash algorithm. Do note however that other mining algorithms, especially more GPU dependent, may need more power for their efficiency sweet spot on the GTX 1080 Ti.
We got a tip about a motherboard that should be capable of driving seven video cards for mining, namely the MSI Z170A Gaming Pro Carbon, so we got one to give it a try. It is a Z170A Intel chipset motherboard for Socket 1151 processors (there are cheap Celerons available for it) and it uses the newer DDR4 memory. The motherboard is even packed with some fancy extras that are of no use for the purpose of mining, but they do increase the price of the product. Also do note that even if a motherboard has 7x PCI-E slots that does not mean that it will be able to work with 7 video cards connected with x1 to x16 PCI-E risers, it only means that there is a chance that it might work. Unfortunately there are actually not that much such motherboards available and the only few are usually high-end boards with a higher price tag and that is making them not so attractive for miners, especially compared to the use of the popular AsRock H81 Pro BTC motherboard for 6x GPU mining rigs.
The first thing you need to do with this motherboard, prior to attaching any external video card, is to make sure it is running the latest BIOS and if not to update it to version 1.7. This motherboard BIOS is just a few months old and is apparently what allows the particular motherboard to be able to run up to 7 video cards, so make sure you have it flashed before continuing.
The next step is to set some things in the motherboard BIOS. You need to go to the Settings \ Advanced \ PCI Subsystem Settings and switch the PEG0 and PEG1 Max Link Speed to Gen1 as well as set the Above 4G Decoding option to Enabled. These are pretty much the only settings you need to set in order to be able to run 7x GPUs, just make sure you set them in the BIOS before you start connecting the video cards otherwise you may experience instability of the system or it even not properly booting and allowing you to enter the BIOS. So set them first and then everything should be working fine, or almost.
You can see that Windows 10 properly sees 6x R9 390 video cards and a single RX 480 GPU connected in the device manager with the video driver installed and working properly. We actually have a weird issue with this motherboard as after setting up what is needed for it to work with 7x GPUs we are not able to properly get inside the BIOS of the motherboard. If at boot we press F9 to enter the BIOS the system just freezes and needs a restart, if we don’t press the F9 BIOS key it boost into the operating system and works just fine with seven video cards mining or whatever. In order to get inside the BIOS of the motherboard however we’ve had to clear the CMOS memory and redo the settings each time. We thought that it might be a KVM issue, but even with direct PS2 and USB keyboard connection we had the strange F9 freezing issue most of the time, even though a few times it worked just fine actually loading the BIOS and not freezing the system.
Anyway, while we are not entirely sure what is causing the BIOS freezing issue when you try to get inside with F9 after you set the required options to make the motherboard work with 7x GPUs everything else seems to work just fine. The system boots and sees all 7 video cards, even if they are different ones like in out 6+1 configuration, and you can run a miner that will see and start using all 7 video cards. So the MSI Z170A Gaming Pro Carbon motherboard apparently works, though there are still some glitches that may need fixing. The only issue with this motherboard is the higher price and that may be enough of a reason to make you stick with the more affordable and problem free use of AsRock H81 Pro BTC for 6x GPUs instead. Still if you already have a 6x or even less GPUs on some mining rigs and you have a suitable power supply an upgrade to a 7x GPU motherboard might be an interesting choice. Then again you would need to replace not only the motherboard, but also the CPU and the RAM as well, because of the newer chipset used by the MSI motherboard.
AsRock is without a doubt the most popular manufacturers of motherboards designed for GPU mining rigs thanks to their H81 Pro BTC model, however lately the company is having trouble providing enough motherboards for GPU miners. There have been shortages of AsRock H81 Pro BTC motherboards and the demand is pretty high with new GPU mining rigs getting built a lot once more. The H81 chipset is getting old and there haven’t been more up to date BTC motherboards getting released with a newer chipset from AsRock either and this is apparently opening up some opportunities fro other manufacturers…
Entering Biostar with their new model TB250-BTC that is apparently intended for GPU mining rigs with up to 6x video cards and to additional 4-pin Molex power connectors onboard, just like on the AsRock Pro BTC series. To our knowledge this is the first motherboard intended for 6x GPU mining rigs with an up to date chipset, based on Intel B250 and supporting socket 1151 CPUs and DDR4 memory. The motherboard even has an M.2 slot available for installing onboard SSD modules, a feature that might also be interesting for some GPU miners. The only problem with Biostar as a brand is the limited availability on many markets or the total lack of such, unlike AsRock that is available on much more markets worldwide. The Biostar TB250-BTC in not the first attempt at such a solution from the company, they previously had the Biostar TB85 motherboard that also came as an alternative to AsRock’s H81 Pro BTC, but it never got too popular since it was also hard to find on many markets and was more expensive.
It is not like there are no other interesting alternatives available to the popular AsRock H81 Pro BTC motherboard with more recent chipsets, but since they are not designed for GPU mining rigs specifically they may not all work or may need some special settings and tuning. There are some interesting motherboards with the latest generation chipsets from Intel such as B250/H270 that come with 6 PCI-E slots and at a good price, though they may need some tinkering with the BIOS settings in order to make them work properly for mining. The price is important factor when building up a GPU mining rig and you don’t normally want to spend that much on a motherboard and CPU, especially if you don’t need any of the extra features or performance provided by the more expensive solutions… lower cost means faster ROI.
If you want to take a look at these alternative offers for possible good choices for 6x GPU mining rigs take a look at the offers from AsRock, Asus and MSI with B250/H270 chipsets that do have 6x PCI-E slots. On these however you need to switch the PCI-E to Gen 2.0 or Gen 1.0 and also force the TOLUD or Top Of Lower Usable Dram setting in the BIOS to 3.5 GB manually and not leave it to Auto mode as it is by default. You may want to make sure that the BIOS of the motherboard you go for has this BIOS option available, as otherwise the operating system may have issues properly assigning resources for all 6 GPUs and they many not work.