UD2H and 4/8 pin power cable


I am building a budget-ish PC with Amd Athlon II X4 620 (AM3) and Gigabyte GA-MA78GPM-UD2H motherboard.

I am using a generic 480 watt PSU which has a 4-pin ATX +12 volt power cable (point2) along with a 20+4 pin power cable. However, the motherboard has a 8-pin socket (point1). From what I read in the manual, you can use a 4-pin cable on the 8-pin socket by using the bottom 4 pins.

I tried doing that, but my PC does not boot. The system does not beep at start and there is no light on the motherboard. The CPU fan spins, hard drive and other devices run though.

Can anyone help me see what I am doing wrong? Do I need a better PSU (more wattage? 8pin connector?)


20 answers Last reply Best Answer
More about ud2h power cable
  1. Not necessarily the bottom 4 pins, but the 4 that allow it. The power connector should only fit into the socket in one way - look carefully at the combo of rounded and squared plastic to match it up.

    Let's assume the CPU connector is OK and system still won't POST. Try these things:
    Physically remove the RAM and re-install, making sure it seats positively.
    Disconnect all drives, both data and power cables.
    Use the Clear CMOS jumper to clear the BIOS settings fully. (once system boots, go into BIOS and set to Optimized Defaults once)
    Do you have a speaker installed? Need one for a beep usually.

    Basically, remove all connections except the power supply, RAM, cpu fan and front connectors. Double check those connections and perhaps disconnect all but on/off switch too.

    Is the monitor known good? If you have choice of connections, use the VGA/Dsub for now.
  2. Thanks 505090, I've been looking for that!
  3. thanks for your reply! I read the list and checked for the pitfalls but its still not powering on.

    On top of that I do not have a speaker in the case so I can't hear any error beeps.

    I wonder if 480 watts is enough...

    edit mongox:
    Removed ram and re-installed, nothing changed.
    going to disconnect all the drives now. Is safe to reset the bios right?
  4. yes safe to reset bios just do not try to reflash it without a stable build
  5. Thanks guys for your quick replies! I reset the bios and unplugged HDD and dvd drive, still does not boot.

    I think its a power supply issue...the manual is a little cryptic explainging the power connector situation. The interpretation that I get is that I can either use 2x4 & 2x12 connectors or 2x2 & 2x10 connectors. But my PSU comes with 2x2 & 2x12 ( 2x12 is made up of 2x2 and 2x10)

    heres a screenshot of the manual
  6. according to the manual you are fine and the 2x2 plug goes in the 2x2 section that does not have the cover on it

    as to 500w spec that COULD become an issue in a fully loaded system with several peripherals; not on a boot up with all extras removed

    all fails take it all apart and try again, I've done it a dozen times before and it is always something stupid usually something on the list above
  7. oh boy!

    actually, come to think of it, none of the connectors or slots had any covers on them :/
  8. Best answer
    Don't worry about the covers, my Gigabyte didn't have them either and said it did in manual. Just make sure it's in the only 4 holes that match up properly. The yellow wires should end up on the locking side and there should only be yellow and black wires.

    Actually, at this point I'd bread-board it. Remove the motherboard and power supply from the case. Set up the board on no-conducting surface - the box with the anti-static bag on top work well. If your front cover switches have long leads, then hook up only the on/off switch - I usually use one from an old computer. If your hands don't shake, you can just short the on/off pins momentarily with a screwdriver.

    Even if you don't want to try it, I'd remove the board and carefully re-install. Something might come up that you notice.

    This link should take you directly to a d/l of an xfx M/B Guide that steps you thru bench-testing your motherboard nicely. Only mfg guide I've ever seen of this.
  9. Hi,

    gigabyte says you need bios F6 for your cpu.

    Maybe the mb bios is outdated and cannot start with this cpu (for now).

  10. Well, he can't update BIOS, or chk current one, with no POST or boot or anything on screen. If you DO want to update BIOS later, remember to do so only from floppy method or within the BIOS, don't do from Windows or gigabyte's automatic method.
  11. if I take out my cpu and cooler, I will need to add more thermal paste right? I dont have any at the moment :/
  12. Well, that's true.

    And brings up another thing that can cause this - thermal paste slopped around and gumming/shorting out the CPU pins or other components.
  13. I plugged in a when I turn the computer on I hear 4 long beeps....I cant find a gigabyte beep code on their site or on google...anybody know what the 4 beeps mean?
  14. On Award BIOS:
    1 long and 3 short beeps are: Graphic card error or graphic card memory error.

    Closest I can find to 4 long beeps

    Did find one mention of 4 long beeps meaning CPU fan malfunction or too slow.
  15. come to think of it the fan is indeed moving rather slow compared to my amd athlon 64 1600

    the beeps are all of the same length, about two seconds long. After it beeps four times, there is a three-second gap and it starts again!
  16. Possiblities: Power Supply - 480watts is plenty if you don't have a separate video card. That is IF the power supply is healthy. Was this a new build with new equipment? Can you give us a make and model for the power supply? Unfortunately some cheap cases come with some very questionable power supplies and some combo deals will do that too. If this was like a $20 PSU (not sure where you are from so I use dollars) then it would be of doubtful quality.
  17. I am using built in video chip.....power supply + the case was around $50. The power supply has no name written on it
  18. turns out it was a memory problem.

    I bought a dual channel kit of two heavy duty (padded with extra materials on the side and a pair of heatpipes over the stick) 1gb sticks.

    Since I couldnt fit them side by side on dual channel cause they are so thick, I put only one of them onto the motherboard. Turns out you HAVE to have BOTH of them plugged in side by side.

    I went ahead and exchanged the sticks for some regular kingston ram and all is well :)

    Thanks a lot for the replys guys!
  19. Good to hear you solved it.

    Ya know, I saw that big RAM heatsink sticking out on the pic a dozen times, noticed there was only one and decided it must related to the CPU or northbridge somehow. Even though it looked like a popular RAM heat spreader by OCZ.

    BTW, there's no reason to suspect a single module would cause an error. All dual-channel boards that I've seen are designed to support a single module if necessary. And often you test a computer with a single module. If you'd mentioned the problems seating the RAM, someone might have jumped on it.

    And indeed, I just read over the Installing RAM portion of your manual, and it only mentions installing two or four modules. Unlike most, it doesn't mention installing one at all - nor has any warning about the need for two. Normally, the manual will discuss the lousy performance of installing a single modules (loss of dual-channel) but will tell you where to put a single on if needed.

    Good luck and thanks for letting us know!
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