S7 /S9 Miner With IBM Server Power Supplies

S7 /S9 Miner With IBM Server Power Supplies

This is mainly a blog post to help eBay buyers who have purchased S7 miners from me, to get them going with the power supplies, but usefull if you want to make the jump to server grade PSU’s rather than the cheap Chinese units available with the miners. Click on the pictures for a closer look.

Photo Of My Bitcoin Mine

Some Of My S7 and S9 Miners

Power Supplies

When I first started mining I used 1200W HP Power Supplies with my Spondoolies SP20’s. They worked well but ran hot as hell and close to maximum load, not good for a power supply running 24 hours a day. I added another Sp20 which I purchased from Spain and the guy out there sent me two old power supplies with the miner which were IBM Power supplies made by Delta. At first Ill be honest and turned my nose up at the units, they were big and looked bulky but they ran cool as hell and were very quiet. Within a week I was buying IBM Power supplies on eBay like crazy and swapped out every HP Supply for two of these beasts. Ive never had a power supply go bad or indeed over heat, so for me the IBM units are the way forward. Not to forget they are cheap as hell if you buy them at just the right time. Ive been paying around £15 to £20 per power supply with free shipping.

Search on eBay for “IBM 1300W” and you will find them easily. Once you see the photos below you will recognise them.

What I like about the IBM power supply is that the copper terminals are just the right size to push a standard automotive crimp right on there. One point to note here is that the crimp will be loose when new and will wobble around. Simply put the crimp into a pair of plyers and slowly crimp the receptacle until the gap at the edges is slightly reduced, then push firmly onto the power supply.

Power Supply Crimp Connections

Power Supply Crimp Connections

Each power supply has eight + and eight – connections but in reality only FOUR per side can be used safely with this method. I find the best way is to push the crimp receptacle onto the far strip with the curls in the crimp away from the PSU post, just like in the photo above. Adjust the crimp by squeezing until the fit is snug and tight. Dont worry about the strips bending, they will and you need to do this so the crimp pushes firmly home.

As the Power Supply is designed to run in a server, it needs to be made to turn ON as soon as power is applied. My contact in Spain sent me two PCB jumpers to use which I lost when I unwrapped the package. So I found a post on an amateur Ham Radio forum which discussed using server power supplies in detail. These power supplies needed two pins shorting to get the power supply to run up. I decided to bend the two pins together and solder them really carefully. This was a quick and easy fix which in some ways I wish I had stuck to jumpers. In the future I will remove the solder from these pins and solder a pair of wires to an Arduino Relay Box or similar, so I can restart the miners remotely. Sometimes a reset at the miner software level wont fix issues.

With the power supply located so the terminal block is lower right, these are the two pins which need to be shorted out to get the supply to run up.

Pins To Short

Pins To Short

And here is how to work out the + and – connections. I always pen these on so I never get it wrong! Look closely, you will see the soldered pins again to help with orienting the power supply.

+ and - terminals

+ and – terminals


The S7 miner needs ten PCI power cables. In the past I have purchased the plugs, crimps and sat down and made my own. Ill never do this again as its very time consuming. Search for “S7 Miner” on ebay and plenty of cables are available to buy. Now I have been critisied in the past for using the clear plastic plugs against the black plastic ones. The difference is that the black plugs can carry more current than the clear ones. The miner comes with clear receptacles so why bother! Just remember that after plugging and unplugging a molex more than a couple of times, the contacts start to wear and loose connections will develop. Keep an eye on the temperature of the connectors to the miner. If they become hot or start to burn, replace the plug straight away. I burnt loads up on my Spondoolies until I figured new leads EVERY new miner. Never had a problem since.

The S7 miner has three hash cards which need three power connectors each plus a connection for the controller card. There is one very simple rule to follow. NEVER connect TWO power supplies to ONE hash card or things will go horribly wrong!

I use ONE power supply to feed TWO hash cards. I get TWO PCI leads and join all the ends into two automotive crimps. When connected to the first power supply you will then use three strips on each terminal. Call this Power Supply One.

I use another power supply (Power Supply Two) to connect to the third hash board and the controller board using FOUR cables. I tend to crimp two cables to one auto crimp then two to another. You will use two strips on each power supply.

PSU Connections

PSU Connections

Just one more important point, turn on Power Supply 1 before Power Supply 2. This way the Hash Cards get power and are seen by the controller correctly. I tend to wire both to one switch now and bringing them both on at the same time is not an issue.

So you should now have the miner up and running using server grade power supplies.


When the miner is up and running you need to find it on the network. Give it five minutes to boot up but when it starts chucking hot air out the end its more than likely working. I generally ran them with an IP address of to If your router is configured using a different IP structure (192.168.1.x is common) then you may need to change it temporarily or just reset the miner. If you need to reset, leave it to run for five minutes then push and hold a paper clip in the reset hole on the rear, until the alarm sounds then the unit will re-boot. It will then grab an IP address from your router.

Download Advanced IP Scanner and get it working prior to turning the miner on. Scan for it (they show as a Texas Instruments Device) and note the IP number. Log into a web browser and type the IP address then the miner will appear and you can log in. Use root for user name and root for password.

They dont come on line as soon as you throw in the power. The unit carried out self tests and has to boot linux into the Beaglebone controller before it comes up. You will get to learn the boot up sequence eventually.

Mining Pools, Heat And Noise

I have tried solo mining, P2Pool and Pool mining. In the early days I pool jumped and thought Im a lucky guy ill be finding blocks all day long. When reality finally hits home im sure that your thoughts of becoming a bitcoin millionaire over night will be dashed.

So, I have stuck with CK Pool over at www.kano.is for a long time now. They are not the biggest or the smallest and not Chinese based. You need to mine here for a few days so that the payment you earn go up. The payment system works on pplns (Pay Per Last Number Shares) so payments ramp up over time. You need to be patient here and trust me it will happen.

Larger pools solve more blocks and pay out more to more people. Medium sized pools (CK Pool) solve less blocks and share with less people but the pay per block is more. Smaller pools solve less blocks and pay out less to less people.

Now in mathematical prediction, luck balances out over time so whatever path you choose we should all earn about the same. However, CK Pool is just a lucky pool overall, always has been and I hope it always will be. This gives a slight edge to other pools and in the mining world ANY edge is an edge to take. Ill stick with CK Pool for the long run.

In the miner settings you can add a pool. The string looks strange but something along the lines of this will work for kano.is. Just register FIRST.

  • URL – stratum+tcp://stratum.kano.is:3333
  • Worker – registered user name.miner name  (eg flameruk.miner1)
  • Password – Not important, DONT use your password simply enter “password”

When you have a user name for kano.is just make up a miner name as above, miner1. If you buy another call it miner2 etc. When you look at the workers in the pool it will appear.

By now you probably have this shiny S7 in the living room with it screaming like a banshee woundering how the wife will ever watch a soap again. You go to bed and hear it through the floors and walls and its driving you mad. Well welcome to bitcoin mining my friends.

So, you stick it in the basement and get a great nights sleep. Finally the demon is locked away and all seems well until you go to see your shiny new friend when you awake to find the basement is at 50 Degrees, your stock of candles are melting in the packets on the sides and  the cats collapsed in the corner due to heat exposure.

Noise and Heat, never under estimate noise and heat. Ill leave this one with you to solve on your own. Luckily I have a large industrial unit but in the summer heat is still an issue to me.

Mains Power Cabling

Each of these miners pull around 1200 to 1300 Watts a piece. On a 230V supply thats about 6A. On 110V that around 12A give or take. Be VERY carefull how you supply power to the miners. One runs fine on a short lead in the UK but it will run hot. The 13A plug will run hot, the socket will get hot. Keep an eye on that just to make sure that you dont cause a fire.

When the bug kicks in, you know, just one more miner ………

Start to consider a very well designed mains distribution system. Two miners on a 13A plug and everything starts to get very warm indeed so just dont do it.

Im really lucky to have three phase electricity so I use 6mm cable to a three phase board and run two miners from each phase. At the moment I have sockets all over the place but im loading all the S9’s into a purpose made rack with spurs to make it just a little safer.

So I hope you enjoy your mining adventure and may it be a safe one!

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