Installed new motherboard, PC will not turn on

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  1. Posts : 29
    Windows 10
       #1

    Installed new motherboard, PC will not turn on


    UPDATE: I smashed some pins on the processor by accident. Amazon is super cool, so I am getting a replacement, however I have a new question. How exactly do I plug the converter in to everything? Like, what goes where? I listed the power supply and motherboard already, if any more info is needed, just ask.

    Hi all. I recently installed a new motherboard, the GA-78LMT-USB3, plugged everything in place, and pressed the power button. Nothing. I have checked to make sure everything is in place, it is. I have the right socket for my cpu, the right power, everything. My only idea is the cords that power the processor. None of them are broken, however, with the power supply I have, the 8 pin cord is split as two 4 pins which can be clipped together to make an 8 pin. When they are clipped, they are not the right shapes (as in the pins that plug in). After discovering that, I bought a 4 pin to 8 pin converter. I plugged that in today, and it wont work. The reason I believe it is the processor is because when I press the power button, my keyboard lights come on, but nothing else. This is what happens when I don't have a processor in at all. What the heck is going on?

    Converter I bought: StarTech 6" 4-pin Female Molex to 8-pin Male EPS Power Adapter with LP4 EPS48ADAP - Micro Center

    Power supply: Corsair RM 550
    Last edited by TheMuffinMan; 01 Jan 2017 at 20:46.
      My Computer


  2. Posts : 13,896
    Win10 Version 22H2 Pro and Home, Win11 Pro and Home
       #2

    That looks like a nice Gigabyte board for the AMD CPUs, I use a couple of older Gigabyte boards, one with the Phenom and the other with an AM3+, quite stable. GIGABYTE - Motherboard - Socket AM3+ - GA-78LMT-USB3 (rev. 4.1)
    The 8-pin plug goes to the ATX 12V socket and my experience is the computer won't boot unless that socket is occupied. The 2x 4-wire plugs should clip together to plug into that socket or they may slide together to form the 8-pin plug. When the 2 plugs are combined they are indexed and can fit only one way. As for the modular power supply, there should have been the proper cables included with it to provide the needed 'legs' for power up everything inside the computer.
      My Computers


  3. Posts : 19,516
    W11+W11 Developer Insider + Linux
       #3

    Which processor, did you change it too ?
      My Computers


  4. Posts : 7,128
    Windows 10 Pro Insider
       #4

    Can you post a pic of the two 4 pin plugs and the socket on the motherboard. I'd like to see why when clipped together they are the wrong shapes.
      My Computers


  5. Posts : 7,128
    Windows 10 Pro Insider
       #5

    If you look very closely at the 12V 8P socket in this picture you can see that the two 4 pin plugs can only go in one way.

    http://img.tomshardware.com/uk/2005/..._jeantech8.jpg
      My Computers


  6. Posts : 29
    Windows 10
    Thread Starter
       #6

    Winuser said:
    Can you post a pic of the two 4 pin plugs and the socket on the motherboard. I'd like to see why when clipped together they are the wrong shapes.
    I can get you one soon, however I figured out the problem. I was a complete moron and smashed one of the pins on my processor. I was heart broken. Luckily, Amazon is charging my money back and I am going to get a replacement. Picture will come sometime today when I can be bothered to open my PC again. Also, the picture you sent me is nothing like my power supply. Here's what mine looks like: http://www.corsair.com/~/media/corsa...50_dc_side.png
    My new question: How do I plug the adapter/converter in to everything?
      My Computer


  7. Posts : 13,896
    Win10 Version 22H2 Pro and Home, Win11 Pro and Home
       #7

    The plugs that go into the power supply sockets appear to me to be specific, can't reverse them. If the Peripheral/SATA ports can connect enough cables to provide power to the drives and maybe add-in video card you should need the adapter. The 6+2 or 4+4 should be the ones for the ATX 12V socket on the motherboard.
      My Computers


  8. Posts : 29
    Windows 10
    Thread Starter
       #8

    Berton said:
    The plugs that go into the power supply sockets appear to me to be specific, can't reverse them. If the Peripheral/SATA ports can connect enough cables to provide power to the drives and maybe add-in video card you should need the adapter. The 6+2 or 4+4 should be the ones for the ATX 12V socket on the motherboard.
    Okay cool. I will try this when I get my processor in the morning.
      My Computer


  9. Posts : 19,516
    W11+W11 Developer Insider + Linux
       #9

    Just watch it, 6+2 can also be PCIe (GPU) supply but it's keyed differently than ATX 12v. (not on the PSU side but other end of cables). Other PSU manufacturers may have different configurations of connectors so mixing cables with others may result in disaster.
    Just as side information, ATX 12v 8pin connector is keyed so other 4 pins are keyed same as added 4 pin connector on 20+4 pin main MB power supply. As I was lacking 8 pin on my old PSU I made an adapter to other 4pin in 8pin ATX 12v drawing power from a Molex 4 pin.
      My Computers


  10. Posts : 465
    W11X64 22H2 X3
       #10

    Here is a pin-out piccy

    Installed new motherboard, PC will not turn on-8-pin-6-pin.png

    Get this wrong & your PSU is likely not to power up at all if it sees a short circuit, your EPS 8-pin shoud fit straight into your board & only 1 on these connectors will fit, then the other will fit the PSU.
    I always buy semi-modular power supplys so the main power conns are hard wired at PSU...
      My Computers


 

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