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Up-Cycling Dell Server Power Supplies

25th September 2018

Cryptocurrencies, in general, are a controversial topic. All decentralised "cryptos" use some sort of algorithm to generate signatures that ensure the integrity and immutability* of their respective blockchain/ledger. The predominant family of cryptocurrency algorithms are known as PoW or Proof-of-Work.

PoW is extremely controversial for a variety of reasons, but the biggest issue with PoW is that PoW requires machines to do... work and "work", by definition, requires energy to be expended. The "work" is generally carried out by a processor (in some recent algorithms novel approaches like "Proof of Capacity" are being trialed).

So "work" needs power and power comes from power supplies. Power supplies are expensive and so any way of making the acqusition of power supplies for mining cheaper improves profitability.

Enter the Dell Poweredge 1950 server, which includes two very beefy power supply units capable of ~49A on 12V apiece... very nice. These servers were released to the market circa 2006, which makes them 12 years old. In the computing world, that's ancient. They're extremely loud and noisy, big, awkward, use loads of electricity and can't really do that much. Unfortunately, they've reached their expiry date. It happens. I've collected several of them off auction sales and some have even been given to me.

A Dell PowerEdge 1950 Server with cap off.
Dell D670P-00 670W Power Supply - each server has two of these.

Innovative peeps have built interface cards for larger variants of these power supplies, specifically for mining operations, but unfortunately, these power supplies are a bit too small to make that kind of time investment viable. A more, er, "DIY" solution is required.

These power supplies are designed to be cooled using ram-air provided by a set of jet-like fans in the main server chassis. The servers are old and hopelessly inefficient, so I won't be using them in future. I therefore removed the fans and drilled holes through the power supply enclosures to provide cooling.

Dell PowerEdge 1950 fans - powering them took a bit of guesswork...
Ghetto as hell, but wood-gluing the fans to the power supplies is cheap and effective.
Fans are "installed" with the airflow directed upwards to take advantage of convection and keep dust accumulation on the outside of the housing.

Next, we need some cables to attach to our power supplies. I removed one set of ends while the glue was drying in preparation for soldering.

PCIE connectors stripped and ready to be soldered.

This is all pretty high-current stuff (made worse by it all being 12V), as such it's important to make sure solder joints are really solid (more so than what's demonstrated in this picture).

A better set of soldered joints.
Two sets of pins need to be shorted to make the power supply run.

And there you have it! A "proper" AND efficient 670W 12V supply. These can be used to comfortably drive 3x overclocked AMD RX580 GPUs. It could probably power 4x GPUs, but as always, it's better to er on the side of caution.

Powering the fans took a bit of guesswork as well as trial and error, but essentially fans have a positive, negative and sensor line. One set of fans use black (GND) and red (+12V). Yellow is the sensor line and for this application remain unused.

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