Building a GPU based Crypto Mining Rig

To build a multiple GPU crypto mining rig, you need to consider the following

1. Density vs price
2. The number of GPUs per rig
3. Power supply
4. Cooling

It is obvious that the more GPUs, the more the cost associated. The good thing about density, is that you have higher hash rate with less cost compared with building multiple rigs to achieve the same hash rate. The bad thing is that it involves paying for the whole thing at once specially the GPUs.

Currently there are 2 GPU manufactures. AMD and Nvidia. Each has their own line of GPUs however it is important to note that there are 2 kinds of Nvidia GPUs. They are LHR GPUs and the none LHR GPUs

1. AMD
   • RX580 with 8GB of memory
   • RX5xxx XT
     1. RX 5600 XT
     2. RX 5700 XT
   • RX6xxx XT
     1. RX6600 XT
     2. RX6700 XT
     3. RX6800 XT and RX6900 XT
2. Nvidia
   • None LHR GPUs
     1. GTX 16xx with 6GB family of cards
     2. RTX 20xx with 6GB family of cards
     3. RTX 3060
     4. RTX 3080
     5. RTX 3090
   • LHR GPUs
     1. RTX 3060
     2. RTX 3060Ti
     3. RTX 3070
     4. RTX3070 Ti
     5. RTX3080 Ti

LHR stands for Lite Hash Rate. It is a technology introduced by NVidia in some of its very successful GPUs to foil crypto miners and get more graphics cards in the hands of gamers. This technology lower the productivity of the GPU significantly and get it produce half of it is full potential on average. There are 2 versions of LHRs currently in the market. V1 of LHR affects only Ethereum mining while V2 potentially affects all mining operations.

Few important points to consider when buying GPUs

1. Each GPU regardless of manufacture has
   • Its own power consumption profile
   • Expected hash rate depending on the algorithm (what crypto currency to mine)
2. Please note that Nvidia RTX30xx family of cards, there are LHR and none LHR cards of the same model (for example, RTX 3060 and RTX 3080)

To get an idea about the expected hash rate and power consumption per card, I would encourage you to visit WhatToMine website. Please note that the value you see on the website are estimates to what you might get. Your power draw might be up by 10% more and your hash rate might be lower or higher depending on the manufacture and the infamous silicon lottery

The silicon lottery is basically the quality of the manufacturing process which results in same cards models from the same manufacture scoring different power draw and/or different hash rates.

Now that you know the basics of GPUs, lets talk about building a mining Rig. A mining Rig is just similar to a desktop computer but with multiple GPUs connected to the motherboard. In a normal desktop computer, you have the following key components inside the case

1. Motherboard
2. CPU (aka processor)
3. RAM (aka memory)
4. Hard disk drive (aka storage)
5. GPU (aka graphics card)
6. GPU Risers
7. Power supply

The good news is that all normal motherboards out there support up to 6 GPUs. To connect more than 6 GPUs, you will need specially motherboards designed for mining. Those mining motherboards can support anything from 6 up to 19 GPUs (under special conditions).

I can’t proceed without mentioning the queen of mining motherboards which is the ASUS B250 MINING EXPERT. That motherboard has 19 PCIe slots to connect up to 19 GPUs. However please note to utilize the full potential of that motherboard, you need to use a specific combination of GPUs from different manufactures (please refer to its manual for details)

For a low density build, you will need

1. A 6 GPU frame to mount all the different components. You can either buy a ready made frame or build one out of wood.
2. A regular motherboard (no need to go fancy at this stage since mining motherboard can be expensive)
3. The cheapest CPU (processor) you can find that would work with your motherboard.
4. 8GB of RAM
5. 120GB SSD
6. 6 GPUs
7. 6 GPU Risers
8. Power supply(s).
9. OS (To make it very simple, I will be using Windows 10)

For a high density build, you will need basically the same components except

1. Bigger frame to hold the number of GPUs you need
2. Specialized mining motherboard that can handle the number of GPUs planned
3. Potentially 2 or more power supplies.
4. Extra GPUs
   • Please keep in mind that AMD drivers support up to 12 AMD GPUs
   • Please keep in mind that Nvidia drivers support up to 8 Nvidia GPUs connected at the same time
5. Extra GPU Risers

Regardless of your rig size, please note your power capacity depends on which GPUs are being installed since each GPU model has its own power consumption profile. To illustrate the power point, below are simple examples showcasing the power consumption issue for different GPUs.

If you are building a rig to mine Ethereum (ETH), then a single Nvidia RTX 3080 none LHR edition graphics card – when overclocked and power tuned properly – will consume approx. between 215 to 255 watts of power depending on the manufacture. Another example is the Nvidia RTX 3080Ti graphics cards which will consume anything from 280 watts up to 310 watts depending on the manufacture. AMD RX cards tend to consume less power in general but produces far less hash rate. To illustrate the point of power consumption verses hash rate when mining ETH see below table

GPU	Approx. power consumption (Watts)	Approx. ETH stable hash rate (Mh/s)
Nvidia RTX 3090	320	110
Nvidia RTX 3080 (none LHR)	255	98
AMD RX6800 XT	160	62
AMD RX6900 XT	160	62

From the table above, it is imperative to calculate the power consumption properly and make sure of the following

1. To know the approx. power consumption of your GPUs in advance
2. You plan to have 20% extra power capacity available
3. Your power socket(s) and wall wiring can handle the power draw otherwise you can blow up your power circuit or worse burn down your house.

The final point that many ignore is cooling. Those GPUs when mining, produce a TON of heat. You need to have a plan to keep them cool otherwise you will end up with lots of issues ranging from stability to potentially bricking your GPUs. To get an estimate about the sort of heat generated by those GPUs, get the sum of their power consumption in Watts and convert it to heat. So for example, a rig that consumes 2000 watts per hour, will be generating heat equivalent to 2000 watts hair dryer running continuously. This sort of heat will in a very short time raise the temperature of room and if left unchecked, will crash the rig or worse damage your hardware.