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Old Aug 15, 2010, 07:08 PM
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How to convert Server Power Supplies

Thought it might be useful to gather this in the one place.
The practice of converting computer SERVER power supplies to make a very high quality high power supply at low cost is attractive. It doesn’t normally require any modification to the supply but the hard part is figuring out how to trick them into turning on. Far and away the best way is to find someone who has already done it. I have put down a few references I know about and welcome additions.

This is about SERVER supplies which often have large 12V capacity and not much else; it is NOT about converting normal PC power supplies. (The ‘ground the green wire and add a load resistor’ stuff). That is covered extensively elsewhere.
UPDATE There are now available supplies for PCs that have substantial 12V rails and large (850-1200 Watt) capacity that work without any electrical conversion. If you have used one of these, suggest you start a separate thread.

Please, please. This is a REFERENCE thread. Just post a link (with comments) to other posts that show how to do it if you know of one that isn’t here.

IF YOU HAVE AN OPINION OR JUST WANT TO COMMENT OR HAVE A QUESTION ABOUT CONVERTING A PARTICULAR SUPPLY please do it somewhere else (like the original threads for example or PM me). Obviously info on sources of supply for these devices is welcome though – please post that if you know it, as well as any errors that need correcting.

Bottom Line: If you have an unknown supply you need help with, try a post in the original 12v 100A supply thread (link 2 below) which seems to have a good range of posters - or start a new one with a specific title that includes your question. That thread now has some good info on how to solve an unknown supply as well. See the first few posts. When/if you ever get it to work, then post the link to that info here to make it easier for others to find.

If you have an unknown supply and can't find the information from someone who has already solved it then this post contains the best information/links on how to establish which pins might turn it on and control the output voltage.

UPDATE: This one contains additional information that is more useful.

Hope this proves useful.

Best post on how to deal with an unknown supply

Various threads containing information on converting different supplies.

1) The original IBM Series 235 Supply which started it all.

2) A simple high quality 12Volt 100Amp Power Supply thread starts here

This is my thread on the HP PROLIANT DL580/ML570G3 which is a 12V 1300Watt supply. It's still my favourite for quality, power, small size and having a proper plug for the power cord BUT it's extremely noisy because of the two small high speed cooling fans. Most people will find its vacuum cleaner impression a PIA. Note that you have to take care to identify exactly which supply by the part number. There is a range of DL580 computers with different supplies.

3) The Compaq HP ESP114 Series 12V 55A Power Supply thread starts here

This is earlb's thread on converting these. Was popular popular and remains a good solution. Decent power but much quieter because they are bigger. Easier to obtain and cheaper as well
The attached picture shows the HP 1300 Watt and ESP114 side by side (thanks earlb). The SMALLER one is the more powerful 1300W supply.

4) Dell A570P-00 570W

5) Compaq Proliant 169286-002 750W plus

6) Sony APS-111 12V 33.3A (Used in CISCO gear). Also known as Ascom Energy Systems Galaxy D0009237

7) HP Power Supply DPS-600PB/700CB

8) hp PS-3381-1C1 PSU

9) My current recommendation is the HP model DPS-600PB series ESP135 PS that is used in ProLiant DL380 G4 Rack Servers. It is rated at 575W, or 47A at 12V. It is compact, quiet and powerful and is easily modified to slow the fan down and isolate the DC out to make a 24V supply from two of them (see below under using two supplies). There is a detailed how-to on T Jin Tech's page here and feathermerchant has them as single or dual (24V) supplies. Akshu's thread (#11 below) on a kit to convert two supplies to 24V uses these ones. They are in the bottom left hand picture below.

Using two supplies in series to get 15 or 24V at high power.

Two of the DL580/ML570G3 supplies for example will supply 2600W at 24V on a 240V supply! Here’s the thread I started on the practice of connecting two supplies in series to get 24 Volts at high current. Becoming more relevant with the growth of 1000Watt chargers.

Feathermerchant on the forums sells these already made up if you don't feel you have the knowledge to do it yourself.


These supplies were never designed to be run in series. Here's a quote from someone who knows what he is talking about. Now we know much more about the internals of these supplies, the DC isolation method (see below) is preferable if you know what you are doing.

I must admit, I am more than a little concerned these days about folks connecting different power supplies in series without a full understanding of the dangers. High powered chargers demand more power, and to get it many people having heard of this practice are haphazardly connecting power supplies in configurations for which they were not designed for and have not been tested or CE certified.

All we can do is fight the good fight and continue to educate people. Every week now I get a call or two with a story about series connecting two random, disparate power supplies in an attempt to get more power - with varying success. I sincerely hope the chances of disaster are infinitesimally small and that most all modern supplies have adequate protection built in to avoid anything catastrophic. My concern is for the people playing around modified industrial or hobby grade equipment who don't understand the physics involved and that their actions may be potentially dangerous.

10) Using two power supplies for higher voltage/capacity chargers: safety issues
See post 183 in particular for conclusions.

An alternative approach that is intrinsically safer

11) And here is discussion of an alternative approach which floats the OUTPUTS rather than modify the inputs.
It has developed into a nice solution with a kit of parts available to make a twin 24V 47A system. Thanks akshu

racerxky has photos of how to isolate the OUTPUT of my original HP PROLIANT DL580/ML570G3 (12V 1300Watt) supply in Post #2 above here:

Here's a thread on using two Dell PE6800 supplies - they are the JD200 model

This is an intrinsically safer solution but does require significant disassembly and work on the supply. You can use the opportunity to add a resistor to the fans though and quieten them down a bit!
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Last edited by jj604; Feb 17, 2014 at 08:42 PM.
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