New PC build doesn\'t turn on.

Apologies in advance if I am going against the site etiquette by posting a request for advice, but I've recently found myself in a most disturbing predicament which I shall elaborate upon shortly. Yesterday I finished building my first PC, and for reasons unknown to me, it's not turning on. Perhaps some people would be kind enough to give me what limited advice they can without physically seeing my build?


Motherboard: Asus M4A78LT-M AM3 Motherboard

CPU: AMD Phenom II X6 1090T ~3.2 GHz

RAM: 2x Corsair ValueRAM 1333MHz DDR3 DIMMs

(The drives and graphics card are not yet connected, so I don't think they are causing the problem.)

PSU: Corsair CX430 (430 Watt)

Case: Aerocool I-Curve+ ATX case

A more detailed problem description:

I've installed (correctly, as far as I can tell) the processor, cpu cooler, and RAM. I've put the motherboard into it's case, yes the correct brass standoffs are in place. The PSU is screwed in place and the 24-pin ATX power connector has been connected to the board, but it goes through an adaptor type thing that I think powers some LEDs on the front panel. The 4-pin power connector close to the CPU socket has been connected. The 2 case fans have been connected to the PSU. An optical drive and a HDD have been installed, and connected to the PSU via Serial ATA power connectors, but I didn't know that the data cables were not included so they are not connected to the motherboard yet. The CPU fan has been connected to the corresponding socket on the motherboard. I have connected a case connector labelled as the "PWR SWT" to the corresponding pins on the mobo as per the motherboard manual.

So, as you may have gathered, all the components needed for a switch-on have been connected. Note that there is no integrated GPU on my mobo, but I have an Asus Radeon HD 6850 to install once I know that the machine can successfully switch on. Now, when I plug the mains cable (yes, it's on at the wall socket) into the back of my PSU and turn the PSU rocker switch to the "I" position, strange squealing sounds eminate from inside the PSU, and also the power and reset switches light up on the front of the case. A green LED on the motherboard lights up. The CPU, case and PSU fans used to spin up for a moment, but now I have plugged and unplugged the 24-pin and 4-pin power connectors a few times this doesn't happen any more. Upon pressing the power button down for a few seconds, nothing happens (I was expecting to see signs of life in the case).

It doesn't help that the power button is touch-activated (think PS3 power key), as it offers absolutely zero tactile feedback when pressed so it's difficult to tell if I'm actually even pressing the switch or not. There are no signs of anything happening when I press the button, save for a slightly different tone coming from the PSU. The motherboard manual is rather vague, but it seems that I am connecting the power switch to the corrent "+" and "GND" terminals on the mobo. When I disconnect the PSU from the mains and switch it off at the back, erratic squealing ensues for several seconds as if there are capacitors discharging or something, and the lights on the front remain lit even though it is disconnected from the mains (at least until the squealing stops).

I must say that the situation has me rather befuddled, so your suggestions would be appreciated if they would save me the effort of seeking professional help with the matter.

-A concerned first time PC builder.
3 answers Last reply
More about build doesn turn
  1. A computer will not POST without the 3 main components
    CPU, RAM, and Graphics. Your board doesn't have onboard graphic and you did not install your graphic card. No wonder it's not working.
    You may also want to disconnect all drives/cables, and take that board out of the case to test it out.
  2. I wasn't expecting it to POST without graphics hardware, but surely it would actually turn on? I'll try that anyway, but not tonight.
  3. A system should at least power up even without the graphic card, but it will not POST when a graphic card or any of the other 2 main components are not installed.
    Since you have plugged it in and you heard a high pitch noise, your power supply may be at fault. Try both power cords and if both give the same results. Take the system to another part of your house and try a different wall socket.
    As for the power switch, you can temporary substitute it with the reset switch.
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