Building a mining rig is simple, if you can put a computer together from components, you have the right skills to build a mining rig. However you will need some fault finding skills as there are many more components so there is more to be at fault.
Best tip is buy more Risers than you need, they are cheap and prone to fault.
You don't have to be too skilled to build a rig, but if it's not for you then you can always buy a prebuilt rig off Amazon or eBay.
Big, Small, Multifunction Crypto Mining Rig?
So the first thing you're going to need to decide is will this be a full time mining rig or will it be part-time and multifunctional gaming rig?
These things will dictate the parts you buy, but also other factors come into play such as noise and heat.
Multi-functional Crypto Mining Rig
You need a case with good air flow and if you're going to use more than one graphics card, then size will be important.
Should you be going with a Single Graphics card build, then you could get away with a small case and MATX Motherboard.
For twin graphics cards, you'll want an ATX Motherboard and a suitable size case.
Now you could go for one Graphics card fitting to your budget, but you're unlikely be able to mine whilst you play games. However if you had two graphics cards you could Game and Mine at the same time.
Get the best CPU you can, the more Cores and Cache the better. A good CPU can keep up Monero mining with the best of the graphics cards. Also you could possibly mine and play games at the same time.
Fractal Design have made quite a good case that fits the bill
If you was to use MATX and Risers, there's room for possibly 3 graphics cards.
Small Crypto Mining Rig
So if you're building a small rig just to mine Crypto, then it's best to think of future plans. Is this a hobby/trial or am I going to scale this up to a big rig?
Should you just be starting out with a very small budget, then it's best to go low cost.
The ASRock H110 Pro BTC+ is a really cheap choice and readily available
Cheap Mining Frame
A cheap Pentium (Skylake) or Celeron (Kaby Lake)
Mining doesn't need a powerful processor, just enough to run windows/linux and the mining software. If you want to mine with your CPU too, then look to something with lots of Cache as you'll want about 2Mb per Core.
DDR4 is the latest and greatest, so prices can be high, but remember you don't need gaming spec ram, so you can find bargains.
There is little point buying anything bigger, miner software is quite small file sizes. Buy from your favourite e-Tailor as they are so cheap now. If you're storing your Crypto Wallets with their blockchains, then you might want bigger, for that consider a 2nd larger non-ssd drive .
Add a Graphics card and your set to go. The Nvidia GTX1060 is probably best bang for your bucks.
Here is a Youtube Video to help with the visual process of undertaking a build.
Big Crypto Mining Rig
So for a bigger rig, it's really a scaled up version of the small. You may even build more than one rig, so maybe stackable is something useful.
Veddha make professional frames which are really good quality and stack. They come in kit form and are easy to build. Also if you have short graphics cards to can reverse the support so it's in the right place, that's what I did with mine.
And for the risers, you'll want VER009S, they have status LED's and are much better quality than the older versions. They have several power connectors to suit your style, they certainly made my rigs much more stable.
How when you build bigger you'll go beyond 6 graphics cards and will need to use more than 1 PSU, a motherboard which is well up for the job is the Asus B250 Mining Expert. It can support upto 19 graphics cards and 3 PSU controlled directly from the motherboard.
For the CPU you'll need one that meets the following criteria
Intel® Socket 1151 for 7th/6th Generation Core™ i7/Core™ i5/Core™ i3/Pentium®/Celeron® Processors
Graphics card wise, you'll be looking at the GTX1080
For the power supply you'll want atleast 80Plus Gold rating, it's not just about energy saving, but build quality, heat, noise, stability and reliability.
For a budget rig with energy efficient graphics cards you might get away with 750W, otherwise look for atleast 1KW,