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Modular Power Supplies Less Efficient Say Makers

It's all about power efficiency these days.

Up until the last few years, few paid any attention to the little box that actually powers a PC--the power supply. Now with certifications like the 80-Plus, we're able to at least distinguish efficient power supplies from the rest of the pack. But even with 80-Plus, more and more power supplies are jumping on the bandwagon, so while product quality goes up overall, things are still not where manufacturers want them to be.

There's more detail to power supplies than can fit in the scope of this article, but we spoke to several power supply manufacturers at Computex and the focus customers put on their units.

Despite modular power supplies being a hot product, don't be quick to grab the up-take. The companies we spoke to told us that modular power supplies are less efficient than those that have their cables hard-wired. The reason being that the extra connection you make, adds resistance, and hence, increases heat and reduces efficiency.

Enermax, Seasonic, and Corsair all told us that if you're looking to maximize efficiency, go for a non-modular PSU.

Are the differences great? No one gave us any hard numbers, but they did indicate that the numbers are measurable. PC Power & Cooling, now part of OCZ, says the same thing:

Due to their look, convenience, and cost savings for manufacturers, modular plugs have become a popular power supply feature. Unfortunately, there has been little or no discussion of the impact of this feature on overall performance and reliability. The fact is, modular plugs limit power by adding to electrical resistance. The voltage drop can be as much as would occur in 2 feet of standard wire. Worse yet, modular plugs utilize delicate pins that can easily loosen, corrode, and burn, creating the potential for a major system failure. That's why professional system builders specify uninterrupted wire!

So in the end, you have to choose: do you go with a modular PSU for cable management and appearance, or do you spring for a hard-wired PSU?

  • B-Unit
    Glad to see the major players getting behind this. I read a couple of articles online talking about this over a year ago and have avoided purchasing or recommending modular PSUs since.
  • stray_gator
    PCP&C always discouraged modular psu's - which they also didn't make.
    Hearing similar claims from other manufacturers (some of which sell mainly modular units), though, give them more weight and credibility.
    I'd still love to see some hard numbers, anyway.
  • theone1
    If two connectors and pin (male female) add 1 ohm (total) then for a 20-40A current you loose 20-40 Watts.
  • theone1
    theone1If two connectors and pin (male female) add 1 ohm (total) then for a 20-40A current you loose 20-40 Watts.
    Sorry My mistake:

    R(loss) = 0.04Ohm (2 feet of 20 AWG wire + 2 feet for return ground)
    Power Loss = I*I*R(loss) = 40*40*0.04 = 64Watt

    This is a power loss of 10% for 650Watt PSU
  • The Lady Slayer
    I'm not a spambot. Just to make that clear.

    Before I bought my modular PSU I did a fair amount of reading and research and in end I decided to go with a Coolermaster Silent Pro 600W. I had heard that Corsair were THE makers of modular PSUs, but in Australia you pay significantly more than the standard US to AU currency conversion due to their popularity. Anyway, in my searching for reviews I stumbled across Jonny Guru, an online reviewer who almost exclusively rates PSUs, and tests them based on many things including whether they are infact 80-Plus.

    He gives the Corsairs (MX620W up to MX1000W) between 9.5 and 10, off the top of my head, and gave the CM M600W a score of 9.0, which I was really happy with.

    Just google his name if you haven't heard of him.
  • EQPlayer
    I'm not worried about giving up a few % of efficiency in order to get modular cabling. *shrugs*
  • brendano257
    I've had two modular power supplies in the past, one of them did fail, although I'm not sure it was because it was modular or not. But if you get something like the Corsair 750TX all you need is a little nook or cranny at the bottom or top of the case to put unneeded wires. (Bottom/Top depending on PSU placement.) In my Antec 900 they actually all fit under the bottom drive bays, which put them completely out of the way and didn't take up any usable space.
  • Pei-chen
    Make sense. Didn't manufactures also said a single jumble rail is better than multiple smaller rail as multiple rail often creates unbalanced load on the PSU.
  • shades_aus
    Add a few % more then for the connector to your mainboard and HDDs, floppy, let's not forget the data cables also, I mean, everything takes power. What about the tin legs for the chips and solder used to conduct between the copper tracks and the chips themselves?
    You would think they are talking about rubbing two sticks together here!.

    Have you actually mesured the difference with a good multimeter? I have, and it says there is no difference. This sounds like bs to me. IF there is any merrit, perhaps manufactures should look at trying different connectors or metals like silver/gold plating.

    I think this all started because one manufacturer has the patent on a form of the modular connector and the others don't want to pay.
    Why not just design one that isn't patented and standardise it.
    All for modular. Cleans up the case nicely.
  • baddad
    0 Ohm's in one inch of wire is the same as 0 Ohm's in ten feet of wire no significant resistance.If there is any lost in modular PSU 's it's so small it's of no impact, sounds to me like they don't want to make them to cut cost.