7 GPU mining rig

I finally recieved all components and assembled my first 7 GPU mining rig. Here is the short how-to manual, to build a mining rig, that supports up to 8 Graphic cards.

Components used:

• Asus prime Z270-a motherboard
• XFX power supply 750 W
• Add2Psu adapter
• i3 processor
• Kingston HyperX SSD drive
• 8GB RAM
• Riser Cables
• Radeon RX480 GPU
• stand

Motherboard

When you are choosing the motherboard, everything that matters is number of PCIe ports. Asus Prime z270a has 7. In addition it has two m.2 ports, and one of them can be turned into PCIe port with adapter. With this motherboard we can achieve a total of 8 mining cards.

Power Supply

Before building the rig, it is important to calculate the consumption of all components. Open this link http://www.coolermaster.com/power-supply-calculator/ and input all of the components you are planning to use. One of the PSU rules is, always add minimum 20% of consumption, so PSU can run cooler and longer. Getting at least gold certified power supply is a smart move, because it can guarantee us, that less electricity will be wasted during running. And belive me, mining rig consumes a lot, so golden certified PSU will pay for itself.

Add2Psu adapter

Instead of buying one big power supply (1500W) I decided to use two 750W PSUs. Power supply with higher power capacity costs a lot more than combining two or more PSUs in daisy chain.

PSU needs a signal from the motherboard to power up and because motherboard supports only one PSU connection we need to provide the signal to the second one. I have seen a lot people just shorting the 2 pins on PSU together to power it up. If you want to have control over your secondary PSU it is advisable to connect it together with add2psu adapter. It is a small board that has connection from primary PSU molex connector to secondary motherboard PSU connection. When it detects power on molex it shortens the secondary one and powers it up.

Processor

If you are not planning to do any GPU mining, selecting the CPU is easy. Just go with the cheapest option that fits your motherboard. Any i3 processor will do just fine.

RAM

Amount of RAM doesn't have any effect on mining speed. The important thing is VRAM (GPU ram). You can select any module, but it is still advisable to use at least 4 GB.

Hard drive

We need to store our operating system and mining software somewhere. A standard SSD drive will do just fine. You need to decide if you are planning to mine in a pool or solo. In case of solo mining you will have to download the entire blockchain, which requires some space and a bigger drive.

Riser cables

Riser cables will enable us to connect multiple GPUs on the motherboard with transferring the PCIe 1x port to PCIe-16, shich is required for GPU. It is advisable to look for a powered riser cable with USB connection. These are safer for your equipment and mininmize the fire hazard. If you can find, try buying the riser cables with 4pin PSU power supply. In my opininon revision 6c works best.

Graphic cards

This is the main part of your rig, where all the magic happens. Pick your "weapon of choice" wisely. Some graphic cards will cost you a fortune but the return on investment can be pretty quick. Finding the right balance between power consumption and hashing rate (computing speed) is the key to success. Some of the good cards are RX470/570 and RX480/580. If budget allows you can go with Nvidia 1080 which costs more, but consumes less power.

Stand or a case

Mounting everything into a standard case is next to impossible. You will have to improvise, use your DIY skills and make a case by yourself or buy one of pre-made ones. Make sure you leave enough space between components for efective cooling. It wouldn't be the best move to burn your house down for these few ethers that you can mine before everything catches fire :)

Assembling the rig

1. Mount the processor and ram onto the motherboard, connect SSD drive and primary PSUs motherboard and CPU power connector
2. With add2Psu join secondary PSU with primary one. From primary one we will power CPU, motherboard, SSD drive and 3 Graphic cards.
3. Connect PCI risers into PCIe ports. Attach USB cable to both ends of risers.
   On the GPU side of riser cables, we need to connect power supply for the riser cables and USB cables leading from motherboard end of risers.
4. Insert graphic cards into the risers and connect power supply to the GPU. Connect first 3 cards from primary and 4 cards from secondary one.

If PC boots up, we are done. Install the windows or linux OS. Make sure you are using 64 bit version and update windows and drivers.