This will be the second video card we will review for this site, as I review the Gigabyte AMD Radeon R9 380 4GB video graphics card. This card is a little bit higher-end than the AMD R7 370 I looked at last time, so it should generate a slightly higher hash-rate when mining Ethereum. According to what I have found researching, I am expecting to get around 20 MH/s when using this card to mine Ethereum. The other big difference is that the Gigabyte R9 380 has 4GB of on-board RAM versus the 2 GB of the XFX R7 370 I reviewed earlier.
The jury is still out on how which will occur first, the hard limit of 2GB being reach by the DAG file rendering 2 GB cards useless for Ethereum mining, or the switch of the Ethereum code base to use PoS for generating new coins. So with the potential for the PoS phase to be delayed, and assuming ETH mining is profitable that long, some suggest only looking at 4 GB cards at this point. There is also the small argument that 4 GB cards will hold a slightly better resale value once they are no longer useful for mining.
One interesting thing I notcied while comparing the different cards online, is that the price difference between a R7 370 4GB card and that of a R9 380 4GB is currently only $20. Thus, one of the things I will be looking for during this review is which model would be the better “bang for the buck” in terms of current mining performance. I was able to purchase the XFX R7 370 I reviewed earlier for $140 each. The 4 GB version of the R7 370 retails for $170, and the R9 380 4GB (reviewed today) can be had for $190.
The Gigabyte R9 380 (model GV-R938G1 GAMING-4GD) is based on latest generation of AMD GCN architecture and features 1792 Stream Processors and 4GB 256-bit GDDR5 memory. This model is slightly overclocked from the factory to 990MHz Core Clock, which is 10 MHz above the reference 970MHz. The memory bus is clocked to 1425 MHz for an effective memory clock rate of 5700 MHz. Other things of note are that this model requires a system with a minimum of a 500 watt power supply, which should pose no problem for most modern computers. If you are looking to setup a dedicated rig as we are in this article, you should be looking at a 750 watt to 850 watt power supply anyway.
Since we will be using these cards for mining, I am looking for the individual contribution of the card to the overall system load. I am expecting this to be roughly 180 watts based upon information found online and the manufacturer’s specs. It is interesting that this model only comes with a single 8-pin power adapter, so this is in itself promising and suggests a lower wattage usage. Low power consumption is a strong feature when you are looking at making an income based upon your mining revenue.
This particular model also has a black metal back plate (shown below), which while nice looking, offers no discernible benefit (for mining) that I can tell. Perhaps it offers a bit of stiffness, taking some of the stress off the PCB?
With the initial overview out of the way, I will put the cards in a mining rig I have setup and get to the mining and initial performance results.
For this rig, I have decided to start out with three R9 380 GPUs as I am unsure of the exact power draw. Depending upon the final power draw I observe, I may add a 4th card to this setup at a later point. While some people prefer to setup their rigs with as many GPUs as they can pack in them, sometimes up to 6 or more, I have found that it is easier and more cost effective over the longer term to keep the amount of GPUs per system to a more reasonable level.
There are a couple of primary reasons for this rationale, the first being I can keep the power supply to a single more mainstream unit. I have found 850 watt modular power supplies to be the sweet-spot for mining, as the higher wattage model tend to rise exponentially in price once past this level. I also stick with name brand manufacturers when it comes to power supplies, as these will be running 24/7 for a long time and I don’t want to go with a cheap no-name brand that may claim high wattage but either burns out components or worse burns my house down. Some name brand power supplies I have used and like include: Corsair, SeaSonic, and EVGA.
The other reason that I have found is that finding a suitable and inexpensive motherboard to run 4 video cards is also much easier than when trying to run 6 or more cards per rig. Some motherboards have better luck than others in this department, but I have found ones that support 4 GPUs reliably to be pretty common. These MBs are also in the sweet spot of $80-$120 range. For mining rigs, you are looking to keep the total system costs down, you are not looking for decked out top of the line equipment that will basically idle away it life, as the real work is on the GPUs. Ideally the non GPU portions should be under $200, with $80 for the PSU, $80 for the motherboard, $40 for processor (Celeron works fine here) and $30 for 8 GB RAM we are already looking at $230.
Taking advantage of sales or rebates is good in this area to help keep costs down, and with luck you can obtain a solid foundation for around $200. I would strongly emphasis not to go too cheap though, thus the price point recommendations, as these are where the quality components lie within. Sure you can pickup a $30 1000 watt power supply, but don’t be surprised when it shorts out the rest of your system quickly negating any initial savings.
Besides bus conflicts or lack of connectors, another reason to not run too many GPUs through a motherboard are that even though GPUs have external power connectors, some amount of power does go through the PCIe bus. After more than about 4 GPUs are connected, this power draw can get to be high enough that you risk burning out motherboard components. There are extension connectors that try to work around this by including an power adapter, or even USB extenders which do work good, however I have found that these “workarounds” often add complexity and depending upon component quality can also lead to performance issues.
As mentioned in the previous review, I like do initial configurations with only 1 GPU installed to keep things simple and avoid introducing too many variables at once, in case I need to troubleshoot problems. In this basic configuration I will install the OS and video card drivers, as well as any needed support utilities, such as TightVNC for remote monitoring. Once I am satisfied everything is setup and working properly, and have done some simple bench-marking, I will install the other 2 video cards.
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