Any way to hookup two (dual) PSU's?

By techshare33 ยท 11 replies
Mar 30, 2007
  1. I'm a light gamer and recently got a new video card (7800 GS) for an older AGP-based system. I've only got a 350 Antec PSU in there now. I really need something larger. Since I'm a computer tech, I have a bunch of new 350Watt PSU's. Is there any way to hook up more than one PSU to the same machine for purposes of powering certain periph devices like a graphics card? Ideally, I'd like to get it on a switch so I could turn it on only when I'm gaming, etc. There is surprisingly little information out there about this despite the high cost of high wattage PSU's. TIA for any help!
  2. kitty500cat

    kitty500cat TS Evangelist Posts: 2,154   +6

  3. techshare33

    techshare33 TS Rookie Topic Starter

    Thanks! I didn't see that writeup. It is fairly straightforward. I guess I could just use the switch on the PSU itself to turn off the "slave" when I don't need it? I was interested to see if anyone else is doing this. I read some crazy stuff about fire hazards, etc. but there doesn't seem to be a logical problem with two PSU's on one machine.
  4. kitty500cat

    kitty500cat TS Evangelist Posts: 2,154   +6

    Well, I don't know much about actually doing it; I just remembered seeing the guide, so I just posted the link.. Somebody else is gonna have to help you here.
  5. Tedster

    Tedster Techspot old timer..... Posts: 6,002   +15

    actually there is ... Tom's hardware Guide ran an article on this sometimes back. However, for 350W PSUs, I don't think it is practical. Their project involved two 500 or 600w PSUs if I remember right.
  6. captaincranky

    captaincranky TechSpot Addict Posts: 12,967   +2,524

    I don't know about with parts on hand but,

    I've seen power supply "sets" (very expensive) that have a separate PSU for the graphics (for high draw SLI) and the desktop. Not sure about the brand. I only mention this because it seemed like the implied motive. I assume you could drive the GPUs alone if you tied the 2nd power supply to the case ground and used only the PCIE connector, to the cards.
    PLEASE NOTE, This is speculation! I would not want to try this without much, much, more research!
  7. KingCody

    KingCody TS Evangelist Posts: 992   +8


    first off, why do you think you need a "high-wattage PSU"???... your Antec 350w PSU should be enough for your system.

    also, if you followed Socrates' guide, you would not be able to simply switch off the secondary PSU. the "dual-psu's" do not run in parallel, they run independently, and simply turn on and off together. if you were to turn 1 of the two PSUs off, anything connected to it would not function.

    cheers :wave:
  8. captaincranky

    captaincranky TechSpot Addict Posts: 12,967   +2,524

    Silly Socrates Says......

    I used to sell stereo equipment. When it came to how much amplifier power anyone needed, it usually was some sort of internal decision based on ego and pride of ownership. Sort of, I'm a hundred watt a channel man, and that's all there is to it. Yeah, okay, I would think to myself. The young ones could never be made to understand that the sound pressure levels were speaker efficiency dependent. Here's a link to a Newegg page for a Fortran Source dual power supply, It should provide all the wattage an ego, a computer, or an electric bill can withstand.
  9. joked u 2

    joked u 2 TS Rookie Posts: 128

    Also, yo make life simpler, you could get an old XT style psu that that has the switch built in and say run your HDD off that and every thing else on the other ATX psu. Or some other comb. If you use the older XT style PSU, you don't have to worry about cutting wires or a lot of work. It is simply plug in and turn it on. But you will have 2 power switches you will have to worry about every time you turn your computer on and off.
  10. captaincranky

    captaincranky TechSpot Addict Posts: 12,967   +2,524

    Socrates Evil Twin Prak-tick-cul-tease Says....

    My theoretical concern is this, "in which order do you kill the power?". If there is still power present at the Video Card, when the power is killed will voltage still be present, and if so would that prevent shutdown, or damage the motherboard.
    Personally, I simply don't care enough to experiment with one of my machines. I would buy a split power supply if I suddenly decided to feel the need for installing an "NVIDIA 10 Million GT" graphics. I don't, hence the apathy!
    Hard drives draw a max of about 30 watts. Soooo.... if the system supply couldn't handle that, well you get the idea.
  11. joked u 2

    joked u 2 TS Rookie Posts: 128

    so true, so true... just spend the extra money and buy a good psu.
  12. Powerpc

    Powerpc TS Rookie

    Dual PSU
    i used this info with no problems but one and i fixed it very simply my only problem was the suggestion of cutting the wires back to the outside of the power supply thus makeing it look like hell in my case i had to replace the cooling fan on the Slave PSU so while i was in there i cut the wires back to the inside of the PSU and capped them with heatshrink if you don't know what you are doing i don't suggest that you open up any PSU!!!
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