PSU blowout

Discussion in 'Gaming and Software' started by daviroo, Nov 6, 2007.

Welcome to the Army Rumour Service, ARRSE

The UK's largest and busiest UNofficial military website.

The heart of the site is the forum area, including:

  1. Hey all.

    I bought a new power supply from pc world on Friday, took it home, installed it and as soon as I fed power to it the thing exploded. I took the entire machine back to pc world to get looked at and the tech guy at the desk started to blame it on the machine being dusty. He then decided that it was because I had plugged the PSU in improperly to the motherboard. This is where you guys could offer me some help.

    The power supply in question was 400w and had a 20 pin main motherboard power lead with an extra 4 pin lead seperate from it in case the motherboard had a 24 pin power requirement. I had actually plugged the 4 pin cable into the processor power socket, which on my motherboard is right beside the main power socket and is also a 4 pin socket.

    According to the pc world tech guy this had overloaded the motherboard because there was too much power being fed into the processor socket. But on checking with a 3rd party computer expert he said that it couldn't have overloaded it because 12v should be coming out of all the leads. I then checked the manuals for both the power supply and motherboard and found that the cable I plugged in was giving 12v of power and the processor socket requires 12v of power.

    After speaking to a pc world manager I was told that all the tech guys in the store were unanimous in their verdict that the place I plugged it into would blow the power supply and the whole motherboard. Could you guys give me your oppinion on the situation?

    If there is any more information you need just ask.
  2. Right, the small 4 pin plug in some PSU's was used mainly to ensure that the PSU complied with a standard Intel set out. The way it worked was that the board wouldn't power up unless the extra 4 pin plug was plugged into the relevent socket on the board.
    We've since moved on to motherboards that have 24 pin sockets and some older ATX power supplies only had 20 pin plugs. The solution was to put an adaptor on that allowed them to be safely connected. a 20 pin socket at one end of a cable and a 24 pinplug at the other. With me still?, good as we're into the final stretch!.
    Just to add a potentially catastrophic twist to the story, some companies ( Dell being one) sometimes use their own wiring layout on an otherwise standard looking ATX socket/plug. The idea is that then you can only use their parts to repair your PC. If you plug a standard ATX power supply to a modded board you'll frag one or the other or both. Same applies if you connect a standard board to a modded ATX PSU.
    So to recap:
    If you plug the 4 pin plug from psu to 4 pin socket on MOBO and the 20 pin to 20 pin connectors, all will be well.
    If you plug your 20 pin PSU into an adaptor and then plug THAT into the 24 pin connector on newer boards, again NP.
    If you mix and match proprietary parts with the universal will end in tears.
    I think that covers it. If in doubt, post with details mate. Bottom line most of the spankers who work in PC world I wouldn't trust to sit the right way up on a toilet seat. I've built a good few computers and upgraded more and for the most part I avoid PC World like the plague.
  3. Thanks for replying.

    My motherboard has a 24 pin main socket plus a seperate 4 pin socket just above, which I was told was used to power the processor. The power lead which was plugged into the 4 pin socket was the 4 pin lead that was meant to go into the 24 pin main socket along with the 20 pin lead.

    Surely it all comes down to the fact that the 4 pin lead gives 12v of power and the socket which it was plugged into required 12v?

    I've been back and forth to pc world 3 times now and have been told that I have to take my pc back up again to get checked out by a 3rd party engineer. What exactly they meant by a 3rd party engineer I do not know, also the fact that the inspection will be done without my presence and the engineer will obviously be getting paid by pc world so I am a bit suspicious about that as well.
  4. PC World are notorious for trying to deny liability for faulty goods. I know of a bloke who bought a laptop and the hinge broke within days. PC World tried to argue that they weren't liable because the laptop was running Linux instead of Windows.

    A friend of mine had trouble with them and went to trading standards. They said they receive complaints about PC World almost on a daily basis.
  5. Just a tad confused here. You mention that the board has a 24 pin socket and that the psu a 20 pin and a 4 pin. Now the thing is that you said "The power lead which was plugged into the 4 pin socket was the 4 pin lead that was meant to go into the 24 pin main socket along with the 20 pin lead" You CANNOT put the 4 and 20 pin connectors together to power up a 24 pin socket. The only way to power up a 24 pin socket from a 20 pin PSU is to use an adaptor lead. You mention that the 4 pin only provides 12v, that may be so but the 20 and 24 pin sockets have 3,5 and 12 volts. It goes without saying that they don't mix.Here link showing the adaptor

    I'm not trying to nitpick or wind you up mate but can you state EXACTLY what you did, that way I can give you better information so you can be better armed when you go back to deal with the numpties at PC world.
  6. It is a bit confusing for me too because I'm not a computer expert myself. The idea of plugging in a 20+4 pin connector to power a 24 pin power socket came from the pc world tech guy, not myself. According to him this was the proper way to wire it. I plugged the 4 pin connector that is attached to the 20 pin one into the slot that is apparently for powering the processor.

    I know this is hard to understand without looking at what's happening so I am grateful for the effort. To aid you I took a screenshot of my motherboard manual so I could explain where I plugged the 4 pin lead into. I uploaded the picture as an attachment. The 20 pin lead was plugged into JPWR2 and the 4 pin lead was plugged into JPWR1. Hope that helps.

    Attached Files:

  7. OK first the good news, the 4 pin connector does go to the JPWR1 socket. Now the bad news, the 24 pin socket requires a 24 pin plug. As you can appreciate, the pins can be misaligned if you put a 20 pin plug onto it, so that you're feeding 12volts to a component that should only get 3 or 5 volts. Thats the bad news. The REALLY bad news is depending which way you did it, the board and/or the PSU will now be fragged.
    If the guy told you to mix the connectors, he was wrong, simple as that.
    If they didn't advise you "you need a 24 to 20 pin adaptor" when you asked them (please say you did) how to fit the 20 pin plug to a 24 pin socket then again they are wrong.
    I have to say my gut feeling here is that whatever happens, there is a real risk that the board and or PSU are damaged so any action you take will be damage limitation and will depend on how far PC world will roll over when you deal with them.
    Beleive me mate, I get no pleasure from telling you this.
    I hope it can be sorted.
  8. The pc world technician didn't mention anything about an adapter. According to him the motherboard can work with just a 20 pin power lead plugged into it and the 4 pin one is just an optional extra if you have any power hungry components.

    Also none of the power cables can be missaligned because they are all shaped so they can only be plugged in one way. If you look on the diagram you can see tiny corners of the sockets are shaped.
  9. Just to tip the applecart a little more. If you havent got a written request that you need an adaptor then bury your head. You won't have a leg to stand on.
  10. Like I said mate the 4 pin one is there for one reason only, its to ensure compliance to the power standard set by Intel. Thats it. The board won't fire up without it. The talk about extra power etc is crap.
    The 24 pin socket reqires a 24 pin plug. Its not 'desirable' its not an option, its required.I've made a few computers and servers I do have an idea how they work.
    The 24 pin plug is wired as follows :
    The 20 pin is wired as follows:
    compare the pins. Then imagine what happens when the wrong voltage is supplied.

    Finally, NEVER assume that a plug 'cannot' be misconnected, of course it can. Seen it, LOL but never done it.
    I'd be intrigued to see what the 3rd party advises but my suspicion is that its goosed for the reasons I laid out in several posts.
  11. Can I ask why did you need a new PSU? Were there problems or another reason?

    From your first post it sounds as if you have plugged the 20 pin main lead in to JPRW2 socket correctly then incorrectly used the additional 4 pin connector (that should fit into JPRW2 alongside the 20 pin) to connect to JPRW1, but this is normally very difficult because usually these leads are very close together and the 4 pin will not stretch and it's obvious where it goes.

    Or you have used the separate "P4" 4pin connector (which should go in the JWPR1 socket) and plugged it in alongside the main 20 pin connector.

    Can you make this clear please?

    Whether a power supply is 20 pin or 24 pin it should also have a 4 pin "P4" intel connector (that connects to JPRW1) as part of the ATX standard.

    If possible can you give us the model of your motherboard and the model of the new PSU that PCWorld supplied you with or even better a quick photo of board and connectors.

    As for dust then this has got bugger all to do with it! That is BS and makes me suspicious of PCW.

    Power supplies fail and statistically they do so at low and high hours ( a sort of U curve) .

    I'll speculate a cheap PSU blew, but PCW say that it was incorrectly installed. I hope everything else in your system is ok.

    Back up your pron folks. :)