Finicky PSU only works with one mobo

I have two computers. Computer 1 is a Dell Dimension E520 and Computer 2 is a Lenovo IdeaCentre K230. Computer 2 has all its original parts, and Computer 1 has a small handful of new pieces, including an Antec 500W PSU, but the original mobo.

Tonight, I tried moving the Antec PSU from Computer 1 to Computer 2, and PSU 2 to Computer 1. I connected everything on both computers, and I booted up Computer 1 (with PSU 2) with no issue whatsoever.

The Antec PSU in Computer 2, however, began a high-pitched whine as soon as I flipped the power switch on the back of the PSU. Computer 2's power button was completely unresponsive.

Worried that I had mucked up Motherboard 2, I quickly removed the Antec PSU and replace PSU 2 in Computer 2. No whining from PSU 2 and Computer 2 booted up just fine.

I put the Antec back into Computer 1, and Computer 1 booted just fine, so I reconnected the Antec to Computer 2, but only connected the 24-pin connector and got the high-pitched whine. I also connected everything BUT the 24-pin connector and got no whine.

JUst to be sure, I triple checked all the connections on the second go round. I honestly have NO idea what's causing this, and was hoping someone out there had some insight.

The sum-up:
Motherboard 1 + Antec PSU: ok.
Motherboard 2 + PSU 2: ok.
Motherboard 1 + PSU 2: ok.
Motherboard 2 + Antec: High-pitched whine and no power-on.
10 answers Last reply
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  1. In short. Just leave it alone. If both systems work there's no reason to mess about swapping PSU's?

    It's likely one system is requiring more power than the other, and the PSU your swapping about isn't capable of supplying the required power. Either that or your missing 4/8pin motherboard power connectors somewhere. I still see no reason to play about with components when you have two working machines.
  2. The secondary situation is a good deal more complicated than what I originally posted. I obfuscated the details only because they have no bearing on the interaction between PSU and mobo, and didn't want to distract from the core issue.

    So, here's the reason I'm switching PSUs. The Lenovo is using the on-board graphics and I just purchased a video card for it. Since the Lenovo PSU is only 280 W, I physically moved the Antec PSU at 500 W to the Lenovo computer to supply for the new video card. Cue high-pitched whine.

    So, the idea of the Antec not supplying enough power is a good one, but not likely, since the Lenovo motherboard is actually receiving an increase in available wattage by a switch to the Antec PSU. Also, I know that the Antec PSU is putting out sufficient wattage for the Lenovo, because the needed wattage of the Dell+Old Video Card > Lenovo+On-Board Video.

    The Dell's older video card will be fine with the Lenovo 280W PSU. After the whine, I wanted to move the new video card to the Dell, since the Antec PSU currently works fine in the Dell, but the Dell CPU heat sink enclosure is physically in the way of the new video card, preventing it from being installed in the Dell.

    So, the only way to make use of the new video card is to use it with the Lenovo motherboard, with the Antec PSU, but this is the only combination of mobo/psu that will not cooperate.

    As to the 4-pin connector, again, a great suggestion, but I unfortunately already checked (and double-checked and triple-checked) that connector. Both the Dell and Lenovo make use of the 24-pin and 4-pin connectors, so it can't be an issue with the connectors not working. And again, in my [somewhat useless] rudimentary testing, the whine immediately began once power was connected through the Antec PSU to the 24-pin connector, before any system power button was depressed, regardless of whether the 4-pin connector was in place, and also regardless of whether anything else was connected to the PSU.
  3. The above detail certainly helped narrow down the issue. However, I'm stumped. Your right in that the Antec 500w should be providing more than enough power, and the fact you have both 24-pin and 4-pin connectors plugged in, leaves me wondering where else the issue could be.


    Have you tried the Antec PSU in the intended build (Lenovo motherboard, but without the Graphics card)?
  4. Once I found that the Antec PSU was still working properly with the Dell, I put it back in the Lenovo and attempted a barebones boot with only motherboard, CPU, RAM, keyboard and monitor connected to the on-board mobo graphics, with everything else (including the new video card) moved entirely or disconnected from motherboard and power.

    I got the same whine and same unresponsive power button.
  5. So the problem almost certainly lies between the motherboard and the PSU. I presume there is a voltage issue somewhere between the Lenovo motherboard and the Antec PSU, however having never used a Lenovo Motherboard personally, I have very little more knowledge on this.
  6. This was my initial assumption, too. I posted to see if anyone knew of a "Oh, that! Just set the jumper on the Lenovo mobo to 'Use an Antec PSU' setting" easy fix that WOULDN'T require a new CPU/mobo to adequately work.

    I'm getting my hands on a friend's spare PSU today, so I can see if the problem is Antec+Lenovo or Lenovo+Everything-except-Lenovo.
  7. could be a crossloading issue

    what atx spec is the existing psu?and what atx spec is the antec psu?
  8. I'm not at home at the moment, but will be in a few hours and can check then.

    I simply assumed that they were both ATX12v 2.something.

    Is there a situation that would allow two PSUs of differing specification to work on one motherboard, but only one work on another board?
  9. this is what the current atx spec revisions stand for

    ATX12V 1.x
    While designing the Pentium 4 platform in 1999/2000, the standard 20-pin ATX power connector was found insufficient to meet increasing power-line requirements; the standard was significantly revised into ATX12V 1.0 (ATX12V 1.x is sometimes inaccurately called ATX-P4). ATX12V 1.x was also adopted by AMD Athlon XP and Athlon 64 systems.
    [edit]ATX12V 1.0
    The main changes and additions in ATX12V 1.0 (released in February 2000) were:
    Increased the power on the 12 V rail (power on 5 V and 3.3 V rails remained mostly the same).
    An extra 4-pin mini fit JR (Molex 39-01-2040), 12-volt connector to power the CPU.[13] Formally called the +12 V Power Connector, this is commonly referred to as the P4 connector because this was first needed to support the Pentium 4 processor.
    Before the Pentium 4, processors were generally powered from the 5V rail. Later processors operate at much lower voltages, typically around 1 V, and some draw over 100 A. It is infeasible to provide power at such low voltages and high currents from a standard system power supply, so the Pentium 4 established the practice of generating it with a DC-to-DC converter on the motherboard next to the processor, powered by the 4-pin 12V connector.
    [edit]ATX12V 1.1
    This is a minor revision from August 2000. The power on the 3.3 V rail was slightly increased, and other lesser changes made.
    [edit]ATX12V 1.2
    A relatively minor revision from January 2002. The only significant change was that the −5 V rail was no longer required (it became optional). This voltage was used only on some old systems with certain ISA add-on cards.
    [edit]ATX12V 1.3
    Introduced in April 2003 (a month after 2.0). This standard introduced some changes, mostly minor. Some of them are:
    Slightly increased the power on 12 V rail.
    Defined minimal required PSU efficiencies for light and normal load.
    Defined acoustic levels.
    Introduction of Serial ATA power connector (but defined as optional).
    The −5 V rail is prohibited.
    [edit]ATX12V 2.x
    ATX12V 2.x brought a very significant design change regarding power distribution. On analyzing the then-current PC architecture's power demands it was determined that it would be much cheaper and more practical to power most PC components from 12 V rails, instead of from 3.3 V and 5 V rails.
    [edit]ATX12V 2.0

    ATX 450 PHF.
    The above conclusion was incorporated in ATX12V 2.0 (introduced in February 2003), which defined quite different power distribution from ATX12V 1.x:
    The main ATX power connector was extended to 24 pins. The extra four pins provide one additional 3.3 V, 5 V and 12 V circuit.
    The 6-pin AUX connector from ATX12V 1.x was removed because the extra 3.3 V and 5 V circuits which it provided are now incorporated in the 24-pin main connector.
    Most power is now provided on 12 V rails. The standard specifies that two independent 12 V rails (12 V2 for the 4 pin connector and 12 V1 for everything else) with independent overcurrent protection are needed to meet the power requirements safely (some very high power PSUs have more than two rails, recommendations for such large PSUs are not given by the standard).
    The power on 3.3 V and 5 V rails was significantly reduced.
    The power supply is required to include a Serial ATA power cable.
    Many other specification changes and additions.
    [edit]ATX12V v2.01
    This is a minor revision from June 2004. An errant reference for the -5V rail was removed. Other minor changes were introduced.
    [edit]ATX12V v2.1
    This is a minor revision from March 2005. The power was slightly increased on all rails. Efficiency requirements changed. Added 6-pin connector for PCIe graphics cards, that aids the PCIe slot in the motherboard, delivering 75 watts.
    [edit]ATX12V v2.2
    Another minor revision. Added 8-pin connector for PCIe graphics cards, that delivers another 150 watts.
    [edit]ATX12V v2.3
    Effective March 2007 and current as of 2011. Recommended efficiency was increased to 80% (with at least 70% required), and the 12 V minimum load requirement was lowered. Higher efficiency generally results in less power consumption (and less waste heat), and the 80% recommendation brings supplies in line with new Energy Star 4.0 mandates.[14] The reduced load requirement allows compatibility with processors that draw very little power during startup.[15] The absolute over-current limit of 240VA per rail was removed, allowing 12V lines to provide more than 20A per rail.

    what could happen is that through the revisions they lowered the 3.3 and 5v amps and increased the 12v specs

    on a cross loading issue your psu might not have enough power on the 3.3 and 5v lines to adequately supply your pc
  10. Alright, here's as much information on the two power supplies as I've got.

    The PSU that does not work with the Lenovo mobo, the Antec, is a 500W ATX12V 2.0 spec.

    The Lenovo PSU is an AcBel PC6001. I couldn't find a label anywhere with details on what specification this was. Going by, it does not have pins 12 or 23 (as well as the normal pin 20) on its 24-pin connector.

    While I'm at it, the model of the Lenovo motherboard is L-IG33.
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