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I have a power supply that I have harvested from an old cryptocurrency mining rig that I'd like to use on a new rig however the PSU only has 8 pin EPS plugs.

There are six 8-pin EPS plugs plus a 20/24 pin motherboard connector.

  1. What would be the best option to convert these to 8pin PCIe for use with graphics cards (for a mining rig I'm looking to build)?
  2. Could fabricating a breakout board (eg through OSH park) be a good solution as I can not seem to find any converter cables from 8pin EPS to 8pin PCIe?
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  • Crimp on new connectors.
    – Tom Carpenter
    Commented Jun 11, 2017 at 11:25
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    Both are 12V. There is no "polarity swap", you just have to put the right wires in the right place.
    – Tom Carpenter
    Commented Jun 11, 2017 at 11:41
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    You literally just have to stick the wires in the right place. There is nothing more to it. You put the 12V wires where the 12V pin are on the PCIe connector and the GND wires where the GND wires are. Why is that so confusing?
    – Tom Carpenter
    Commented Jun 11, 2017 at 12:30
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    What Tom says is this: Since the signals are the same (12V and GND) you can extract the pins from the connector and rearrange them to suit the PCIe standard. However, the shrouds are not compatible.
    – Lior Bilia
    Commented Jun 11, 2017 at 15:24
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    @Nepaluz If you look at Tom's comment from the 11th, where it says "buy an adapter" is a hyperlink to an example of such an adapter.
    – Andrew Morton
    Commented Jun 13, 2017 at 12:10

1 Answer 1

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The EPS plug is an 8pin connector which has 12V cables and GND cables.

The PCIe plug is an 8pin connector which has 12V cables and GND cables. It also has two sense pins which as per the spec can be connected to GND if unused.

The connectors are wired as follows: Connector Comparison

So:

  1. Chop off the EPS connector shells and throw them in the bin.

  2. Then you buy new connector shells for the PCIe 6/8 connector (you could buy just the 6-pin connectors and get a 6-pin to 8-pin adapter cable, but no point if you are going to the trouble of recrimping).

  3. Crimp on new contacts to the cables from which you removed the EPS connector

  4. Plug in the new contacts in the corresponding locations on the PCIe connector shell.

  5. That is all. No electronics need. You literally just need to make sure the 12V cables go to the places marked +12V and the GND cables go to the places marked GND.

Alternatively, buy an adapter cable. Search for "EPS12V to PCIe" and you will find several. This is such an example (no affiliation implied). It simply crosses the wires over, no electronic components required:

Example adapter cable. No electronics, just swapping cables

Image Source.

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  • Forget it! I am aware of the wiring and made it clear in my initial response to your shallow answer. If you can not even point out the elephant in the room that the polarity is switched, why bother respond?
    – Nepaluz
    Commented Jun 11, 2017 at 21:12
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    @Nepaluz Yes, the wires are in different places, I think I've made that abundantly clear! But it isn't a polarity reversal, the ground is still the ground, the +12V is still the +12V. It's just where they happen to be in the connector that changes.
    – Tom Carpenter
    Commented Jun 11, 2017 at 21:58
  • Just wanted to confirm for future readers, Tom is correct. The polarity is not switched. It's still +12V, the pins are just in a different location. As an example, I have a modular PSU with multiple 8-pin ports where optional cables can be plugged in for EPS12V, PCIe 8-pin and PCIe 6-pin plugs. The pinout is the same on the PSU side for all of the 12V cable types. Just the wiring order at the device end is different.
    – SirNickity
    Commented Oct 2, 2020 at 18:42

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