All About BTC, LTC, ETH mining as well as other alternative crypto currencies
We’ve recently built a Scrypt mining rig consisting of four AMD Radeon R9 290 by XFX for a friend and since this was actually our first rig with Radeon R9 290 cards we’ve had some interesting findings that we decided to share with you, so if you have some of these troubles we might be able to help. Aside from the four XFX video cards we’ve used an EVGA 1300W PSU (you can see the total system power consumption of 1282W from the mains), Intel Celeron G1820 processor and AsRock H81 Pro BTC motherboard, together with 4GB and Windows 7 OS. For the video cards we have used PCI-E x1 to x16 USB 3.0 Extenders with 1 meter long cable and the cards did not have any trouble working like that. Note that the Radeon R9 290 cards are not considered to be the best option for Scrypt mining, however with R9 280X cards harder to find some people decide to go for the more easily found 290 or 290X models. But unlike with Radeon R9 280X, the R9 290/290X cards have more specifics and could cause you some extra headaches until you finally make them work as they should and provide decent hashrate without problems.
The average hashrate we got from the cards running at stock frequencies of 947 MHz GPU and 1250 MHz video memory got us about 857 KH/S per card or a total hashrate of about 3.4 MH/S. This is what is considered a fairly good results for Radeon R9 290 cards and unfortunately overclocking these cards did not help us in getting higher hashrate, not that we wanted to overclock them as they are already getting quite hot mining Scrypt cryptos. It seems that XFX’s cooling is not that great for mining crypto coins as the temperatures of the VRMs gets easily over 100 degrees Celsius and that is not that great for 24/7 mining even though they are probably rated at up to about 120 degrees C or even a bit more.
One very important thing in making the AMD Radeon R9 290 or 290X cards is how you call up the cgminer, because you need to use a high thread concurrency value that often tends to bring some issues with cgminer. In order to ensure that you can start cgminer without problems you can start by using the command lines below to call cgminer.exe from a BAT file:
start /realtime cgminer.exe --scrypt -o stratum+tcp://us-east.multipool.us:7777 -u yourworker.1 -p password --thread-concurrency 22516 -g 1 --lookup-gap 2 -w 512 -I 20
Note that sometimes even after calling cgminer with the above commands and save a congif file and then you run cgminer.exe directly and it loads up the config file you can still get errors. So if you want to use the config file after you start cgminer with the above commands and save them in config just remove all of the parameters from the cgminer.exe start line, but still start the miner with the BAT file!
Another very important thing regarding the use of AMD Radeon R9 290 video cards for crypto mining is that these video cards do not feature any analog video outputs, so if you plan on using the mining rig without a monitor connected to a card, then you might have trouble. And you cannot just make a dummy plug with resistors, you will need to get an HDMI to VGA or Display Port to VGA adapter to plug in in one of the available video outputs and then add resistors to the VGA output side. This is the recommend solution that can save you some trouble in making the mining rig function properly or if you want to control it remotely with TeamViewer for example. If you have a digital monitor connected and are going to be controlling and monitoring the mining rig with Radeon R9 290 cards then you don’t need to bother with digital adapters to VGA.
Due to the demand for GPU mining rigs for cryptocurrency generation that are capable of powering more than 2 video cards (what is normally enough for gaming needs) some motherboard manufacturers have come up with specialized products especially for GPU mining needs. One such brand is AsRock that already has two specialized motherboards designed for GPU mining rigs and though the company uses Bitcoin mining all over these products, they are essentially for Litecoin and other scrypt-based alternative cryptos. Nowadays there is no more point in mining for Bitcoin with GPUs, you need to use specialized Bitcoin mining ASIC devices (for other SHA-256 cryptos as well), however scrypt mining and Litecoin in particular is still mineable with GPU. And a lot of people are still building new GPU mining righs with multiple video cards for mining Litecoin, so AsRock’s products can be ideal for these needs.
AsRock offers 2 models of specialized GPU mining rig motherboards, one is the cheaper AsRock H61 Pro BTC, designed for Intel Socket 1155 processors and the other one is AsRock H81 Pro BTC, designed for use with Intel Socket 1150 CPUs. Other than the use of different processors these two motherboards are pretty similar in what they offer – support for up to 6 video cards, though you will need to also use PCI-E x1 extenders to attach all of the video cards to the motherboard and you will also need a special rig designed to contain the 6 video cards. These motherboard also have additional 4-pin molex connectors that you need to connect in order for the motherboard to supply enough power to the video cards over the PCI-E slots.
Also if you plan on using all 6 PCI-E slots with GPUs you may need to be careful what OS you are going to be using in order for the operating system to be able to see and use all of the cards at the same time. Linux is a good option for 6 cards at the same time, and there are specialized Linux distributions available for mining rigs. The problem with Linux however is that the control of voltage of the GPUs may not work with all video cards, in fact with most you my have trouble changing the voltage of the GPU, though the clock frequencies are accessible and you can change them for better performance and higher hashrate. So also do have that in mind when building a GPU mining rig.