[How To] Improove the efficency of external drives | PSU modding

  • How to find out if this mod is for you?

    • Touch your power supplies. Hot = inefficient => Go for it
    • More external HDDs = bigger savings
    • You must be willing to modify your PSU cables which voids warranty or do additional tinkering with adapters to the existing plugs
    • HDDs must stand close to mining computer. Long wires may have too high voltage drops

    Usecase scenario

    • 10 external drives with 15 watts average
    • 10 50% efficency powerbricks
    • 80 plus Titatnium grade PSU: 96% efficiency at 50% load


    • 150 watts power draw + 150 watts radiated heat with cheap powerbricks
    • 150 watts draw + 6,25 watts radiated heat with PSU
    • 143,75 watts difference
    • 0,24€/kWH in my town
    • 302€ annual savings

    What do you need?

    • Your mining computer with internal PSU or a seperate PSU
    • Basic soldering skills
    • Soldering iron & solder
    • Connectors: Very cheap to get in 10 packs or salvaged from the included powerbrick
    • Shrink wrap or electricians tape

    What is the goal?

    • Use the highly efficient internal PSU to reduce wasted energy
    • Reduce clutter by removing powerbricks and powerstrips

    Step by Step Tutorial
    Find out if your PSU is suitable

    • Check the energy efficiency of your PSU. If it isn't good, this mod won't work well
    • It must be rated to handle enough current. Rule of thumb: Your PCs requirements + 20 watts per drive. If unsure, use a calculator like this to determine total draw: https://outervision.com/power-supply-calculator

    Make a plan

    • Identify the best rail to tap into. You will find a sticker on your PSU telling you how much load rail can handle. Identify a 12 volt rail that has enough amperage. If possible avoid putting the drives on the same rail as other devices
    • Check which cables are connected to this rail. If your PSU is modular find the best suited cable
    • 6 pin (75 watts) and 8 pin (150 watts) will provide a lot of end points to solder onto

    Execute plan

    • Route the cable out of your case
    • Cut of SATA/Molex plug and solder connector onto it: Yellow is +12 volts, black is mass
    • Isolate it with heatshrink or tape
    • If your cable has sleeving you can remove it to route each wire better to the HDDs

    Results in a bit of a clutter by branching out the original strand of wires into seperate ends

    Alternative plan (better looking)

    • Group all yellows and all black strands and solder each bundle onto a wire or copper strip
    • Create a T junction for every plug
    • Isolate everything properly

    Creates two straight rails with plugs attached

  • @SnipX, nice post. This would be worth doing just to get rid of the tangle of power cables, transformers, power strips, etc. You are exactly right about the very poor efficiency of the power bricks. The one thing I would recommend since you are bringing PSU power outside of the PC case is fusing. Yeah, it complicates things, but it also protects your investment.

  • @Evo Thanks for the feedback. Please correct me if I'm wrong. But I think a fuse would only be of use if you create a shortcircuit? I that case it would protect only the PSU. And modern PSUs should shut down automatically if you draw too many Amps.

    The only real risk I see here is a bad PSU that creates overvoltage and fries all HDDs at once. And according to Murphy's Law it will fry your rig through the USB cables as well ^^

  • @SnipX, yes, a fuse or fuses would only be there to protect the PSU and wiring if one of the external cables had a short circuit. Hopefully the fuse would isolate the problem and the rest of the rig, the PC and the other drives alike, would continue to work. I'm an engineer and I used to design control panels, so I tend to err on the safe side.

    But I don't want to take anything away from your post, it was well done. I like the idea of the rails with just little power stubs. I found a bunch of spare power harness parts that shipped with my last PC, and I think I'm going to take some measurements to see how much spare capacity I have on my PSU's. If the numbers look good I think I'm going to give this a try. I'm tired of the mess the power cables and the transformers create. Thanks again!

  • @SnipX very nice, thx!

  • I found that probably the easiest way is to use a PCIe power extension cable and solder to that. Plugs in and out very well, can deliver 150 watts (8 drives) and can be ordered from china for less than 2$

  • Looks like a nice guide. Would like to see it maintained and extended over a longer period of time.

  • look at miner psu for asic or leds or cctv systems you can get multi tailed ends that fit most hdd enclosures


    i know it is not your psu but my main point is. The squid end with one brick at a higher amp is more efficient than vastly under running a psu to 1/3 of its capacity. If you look on the back of some silver or gold rated psu you will see a curve of efficiency if you underload most atx supplies they are worse than the bricks but at around 80% rated load they jump to 80-90% efficiency.

    There was a expansion slot cover with a 12v power jack that i saw once...

    SInce efficiency is not typically advertised on power bricks the method for determining if you have a good one or not is to plug it into a kil-o-watt meter and if at 0 load it draws detectable wattage it is not a efficient one move to the next...