PC won't turn on and makes weird humming noise

I basically spent the entire day (yesterday) assembling a new pc and after a few minor problems I got it up and running, After installing windows, all the drivers, and just finishing the last few updates.
Turned the machine off, switched the power off (via the switch in the back of the psu) and hooked up the storage HDs, when I returned power to the machine all the fans immediately started and there was a strange humming noise; like the fan is speeding up and slowing down but with a lower tone.
The machine is now completely unresponsive and after I turned off the power and unplugged it, removed the HDs, SSD and cd drive (which were working normally) and everything from the back (mouse/keyboard/monitor) so I move he machine out and get a better look inside. When I turned the power on the fans turned on but a lot slower and the humming was almost gone.

I really need help figuring out what happened.

http://pcpartpicker.com/user/tole/saved/1FB3 this is my build
Just tried to turn it on again after leaving it overnight and it turned on, with the case power button, but after that it didn't respond when I tried to turn it off so I turned it off with the psu power switch and now its back to the same nonresponsive state with the fans (all of them) twitching as soon as I turn the psu power switch.

The humming from last night is replaced by a low pitched squeaking noise each time the fans twitch.

(sorry for double posting the edit button disappeared on me)
Tried removing 1 stick of ram and it booted up, then I tried plugging in the SSD but it didn't boot this is how I found that the order in which I plug things in makes the difference.
If I plug in the main 24pin and 4pin cpu power cables last it boots but if I plug something into the motherboard while the power main and cpu connectors are plugged in it won't boot (the power button won't do anything) and the fans will start immediately after the psu power switch it turned on.

It also boots with 2 sticks of ram if nothing else is plugged in...
Got it working, after about a day worth of experimentation it turns out that in order to have everything work the 24pin main and 4pin cpu connectors have to be plugged in after any new hardware is installed into the motherboard.

So to install the two drives (or anything else) I had to install them then unplug the main and cpu connectors then plug them back in. If I try to plug something into the motherboard, like ram or any SATAs or cards, then the whole rig refuses to start up and the fan goes into passive mode as soon the power is flowing.

I'm not sure if I got a defective board or if this is a comparability issue or if all AMD builds are just this finicky...but now that I figured out that little caveat the machine runs like its supposed to.

ps. That humming also happened with an old psu and the new psu worked fine in my old machine. All the hardware tests I did showed that nothing was wrong.


Posts: 2,887   +628
Yeah, that seems very strange. You did have the PSU unplugged from the wall, correct?


Posts: 1,020   +56
Hi trintim, Well I've built a few pc's and with a fault like you had, I would suspect a short to the case, with the PSU shutting down to save itself.
I would have taken the whole lot apart and really double check the 'stand-offs' between motherboard and case, I had trouble there before.
Then I would have added 'C' drive, a minimum amount of RAM and test again.
Then each stage it works at, prove it, switch off, add one more component, test again.
But some faults are tricky to sort, but great when you do.
I'm having a similar issue with my build, my computer is making a humming noise from the speakers I have plugged into it, but I can't get any fans to run or any devices to power up.