20 to 24 pins using 2 power supplies

Instead of putting out a lot of money towards a new PSU with the current 24 pin main connector, would it be possible to connect 2 older 20 pin PSU's "rigged" to supply the extra 4 pins from the 2nd PSU?
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  1. Do you own and know how to use an ohm meter. You may use two PSUs in a single computer AS long as you DO NOT place the outputs in parallel. Ex. you could use one PSU to power say the HDDs/DVD drives and a 2nd PSU to power the Mother board. Normally +12V1 goes to the mother board. If you ohms check the +12V connectors, on the motherboard, where you plan on connecting PSU #1 and to where you want to Connect PSU2 too and the MB pins indicate that they are shorted together on the MB - Then DON'T. If the two points are isolated then you may.

    Power Supplies differ from batteries in that you can place batteries in Parallel (The cells will equalize). Power Supplies can not equalize and one PSU will "Sink" current from the other. This may cause one of the PSUs to go to that great PSU in the Sky place and possibly thake the other PSU and MB along as company..
  2. ^5 +1 what dallasjoh said. Just use an adapter. No need to to buy a new power supply and no need to rig two older power supplies. No muss! No fuss! No bother!
  3. to answer your question in a word, no. it'd be unwise to connect >1 psu directly to the motherboard. they sell 20 to 24pin converters; but dont ever connect >1 psu to the same object.

    hmm. i seem to recall 1-2 years ago someone was briefly selling a graphics psu which was intended as a second psu purely for gpu. anyone remember that?
  4. rkaye - Yes, using a second power supply has come up nurmous times over the years and there are secondary power supplies available for overloaded systems. Some of them are designed to fit in a drive bay and some were external units. However, it is much easier and cheaper to just use the adapter since overload is not an issue in this situation.
  5. The one caveat is that you really should use a good quality 20 pin PSU with possibly even more wattage than you'd think you'd need if you're going to use that adapter. 24 pin motherboards tend to require more power, to power PCI-E cards and hungry procs. A poor quality 20 pin supply or an underpowered one can cause problems.
  6. bliq - Excellent comment! :) I missed that :(

    basstrx - Please post the brand and model of your old power supply and your pc components. Let's make sure your power supply can easily power your system.
  7. Thanks for all your input on this. I have a fairly descent amount of electronics training, and know, or should I say "use" to know a lot about computers, I have been "out of the loop" so long that to my surprise, 24 pin PSU's as well as PCIe cards and motherboards were knew to me.

    What happened was I found a Dell XPS 400 machine in the trash, and it was fully intact inside, except it had no memory. After loading it up with 4GB's, I realized the PSU was completely shot using a meter.

    Since I am a bit of a crippled-stuck-in-bed kind a guy, I'm on a very fixed budget, but have boxes full of parts/old 20 pin PSU's etc. I am trying to avoid spending cash I do not have on a real good PSU, since with all the reading I have been doing, it seems it's not worth using a 20 to 24 pin adaptor (due to the video card demands), or buying a real cheap PSU for under $40.

    So, considering it was "free", I want to turn it into a gaming pc so I can play the current games. I currently have a custom system of a Soyo KT400 DRAGON Ultra Platinum Edition Board with a VIA VT8377 Apollo KT400 chipset, AMD Athlon XP, 2000 MHz 2400+ processor, and a nVIDIA GeForce2 MX/MX 400 Graphics card and 2 GB Ram in the system, running XP Pro SP3.

    Now that's old considering it was even built out of spare parts lying around. and here is the Newer system specs of the Dell XPS400:

    Pentium D 3.2GHz, 945P chipset, 4GB 800MHz Ram, 1 250 GB Sata HD, and a ATI Radeon X300 SE Graphics card. Unsure of exact Motherboard, but it has 3 PCI slots, 1 PCIe x 1 slot, 1 PCIe x 4 slot, 1 PCIe x 16 (graphics) slot.

    The dead PSU specs:

    Dell Power Supply L375P-00 (I heard these models suck from various sites)
    DELL P/N: P8401
    P/N:PS-6371-1DF-LF
    DC OUTPUT: 375W
    SERIAL#: B 00717248

    P1 - 24 PIN ATX main power
    P2 - ATX 4 PIN
    P3 - SATA (black)
    P4 - 6 PLUG/5 PIN
    P5 - SATA (jumpered off of P11)
    P6 - n/a
    P7 - FLOPPY (jumpered off of P10)
    P8 - MOLEX 4pin
    P9 - MOLEX 4pin (jumpered off of P8)
    P10 - MOLEX 4pin
    P11 - MOLEX 4pin
    P12 - PCI Express 6 PIN (black)

    I am listing this stuff because I was asked to do so, as far as my old PSU's, they are all random wattages, inbetween 175w-400W, and I have about 30 of them, and they all work. But they are older 20 pin types. Various makes/models.

    Anyway, to get back to topic, since the system was "free" and the PSU was most likely the only problem, and all I did was throw memory in it, I do not want to spend a lot of money. So I was just wondering if it was at all possible/worth it.

    Maybe I will just buy one anyway whenever I can.

    Thanks for the info everyone!
  8. The dead psu is a Dell 375 watt model. If you have a 400 watt psu lying around and it is in good working order, then you could give it a try and see what happens.
  9. basstrx said:


    Dell Power Supply L375P-00 (I heard these models suck from various sites)
    What you heard was wrong.
    The 375w from that era is a Newton/Delta with plenty of power for the system it was in and allowed for a decent amount of upgrades.
    I happen to have a spare, PM me and we'll see what we can do for you.
  10. I bought a 400W PSU for $20. all is good.

    Thanks all.
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