New build doesn't switch on.

[Flat Mop]

Apologies in advance if I am going against site etiquette by posting a request for advice in the wrong place, but I've recently found myself in a most disturbing predicament which I shall now detail. I've just finished building my first PC, and for reasons currently 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?

Specs:

Motherboard: Asus M4A78LT-M AM3 Motherboard
CPU: AMD Phenom II X6 1090T ~3.2 GHz
RAM: 2x Corsair ValueRAM 1333MHz DDR3 DIMMs
PSU: Corsair CX430 (430 Watt)
Case: Aerocool I-Curve+ ATX case

(The drives and graphics card are not yet connected, so I don't think they are causing the problem. Someone else on another forum told me that a computer can't post without a CPU, RAM and Graphics processor, but surely it would still turn on without a graphics card?)

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'm afraid to say that the situation has me stumped, so your suggestions would be appreciated if they would save me the effort of seeking professional help with the matter.

tl;dr my newly built PC won't boot, and as far as I can see everything is connected as it should be.

 

[stahlhart]

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.

I'd have to see a photo of that. I wouldn't run that connector to anything besides the motherboard.

I would think that you'd get at least part way through POST without a GPU plugged in (though why you'd want to boot up blindly like that escapes me).

 

[MagnusTheBrewer]

The power switch on your case is simply a logic switch. The power to run your computer does not flow through it which is why you can use a screw driver to temp. short the two pins it connects to for powering on.

You need to start at the beginning rather than trying to troubleshoot your current situation. Try the MB out of the case with just one stick of ram and your GPU. Be sure the one stick of ram is in the correct slot for that configuration. Make sure your case connectors are properly oriented for pin one. Do not rely on the cable labels. Look for the triangle on each pin. With one stick of ram, your GPU and monitor connected (no HDD yet) try to boot. If no joy, try the other stick of ram. If it boots, turn off and add other stick of ram and try to boot again. See where I'm going? Do one step at a time until all cards and drives are connected and system boots. Then, install in case. Make sure both power cables are connected to MB and any auxiliary power cables are connected to your GPU. Do your case fans power on?

 

[Flat Mop]

@Magnus Ok, tommorow I will try reconfiguring everything outside the box with minimal components, but won't powering the mobo up outside without any standoffs short it out?

@stahlhart I will try to post a photo of the 24-pin connector thing, but connecting the PSU directly to the motherboard didn't seem to help.

Should I be concerned about the squealing noises my PSU is making? Could they be indicative of a faulty unit?

 

[MagnusTheBrewer]

@Magnus Ok, tommorow I will try reconfiguring everything outside the box with minimal components, but won't powering the mobo up outside without any standoffs short it out?

@stahlhart I will try to post a photo of the 24-pin connector thing, but connecting the PSU directly to the motherboard didn't seem to help.

Should I be concerned about the squealing noises my PSU is making? Could they be indicative of a faulty unit?

No, powering it up while outside the box is fine. Just use a piece of cardboard between the MB and your desk/table. I generally use the MB box. In addition to the 24 pin power adapter, there is usually a 4 pin power supply that also must be connected to the MB.

 

[stahlhart]

@stahlhart I will try to post a photo of the 24-pin connector thing, but connecting the PSU directly to the motherboard didn't seem to help.

That just seemed like an unlikely place to tap off power for case lighting -- I'd sooner see it run to one of the PSU's 4-pin Molex connectors. I guess it's no big deal.

Should I be concerned about the squealing noises my PSU is making? Could they be indicative of a faulty unit?

It may just be loose windings of inductors on the supply's circuit board -- if it becomes really annoying, you could try a different one. Probably not a cause for alarm.

 

[mfenn]

The power switch on your case is simply a logic switch. The power to run your computer does not flow through it which is why you can use a screw driver to temp. short the two pins it connects to for powering on.

You need to start at the beginning rather than trying to troubleshoot your current situation. Try the MB out of the case with just one stick of ram and your GPU. Be sure the one stick of ram is in the correct slot for that configuration. Make sure your case connectors are properly oriented for pin one. Do not rely on the cable labels. Look for the triangle on each pin. With one stick of ram, your GPU and monitor connected (no HDD yet) try to boot. If no joy, try the other stick of ram. If it boots, turn off and add other stick of ram and try to boot again. See where I'm going? Do one step at a time until all cards and drives are connected and system boots. Then, install in case. Make sure both power cables are connected to MB and any auxiliary power cables are connected to your GPU. Do your case fans power on?

:thumbsup: OP, since you don't have graphics integrated on your mobo, the PC won't do much but beep at you if you don't have a graphics card plugged in. If you don't a PC speaker connected, it won't even beep!

 

[MagnusTheBrewer]

So, any updates? Did you let the blue smoke out?

 

[mfenn]

So, any updates? Did you let the blue smoke out?

Wanna take bets on whether or not it started working when the OP plugged in the GPU? :awe:

 

[MagnusTheBrewer]

Wanna take bets on whether or not it started working when the OP plugged in the GPU? :awe:

I wager 15 Quatloos.

 

[mfenn]

I wager 15 Quatloos.

Done!

 

[Flat Mop]

Sorry guys, looks like Magnus just lost those 15 quatloos. The problem wasn't that it didn't boot, it was that it didn't even turn on. I found out that was because the power switch wires were connected to the wrong pins on the mobo (they were connected to the reset pins), which is wierd because I connected those wires up as shown in the motherboard manual. I got some signs of life from that, all the fans stayed on after pressing the power key.

 

[philosofool]

Sorry guys, looks like Magnus just lost those 15 quatloos. The problem wasn't that it didn't boot, it was that it didn't even turn on. I found out that was because the power switch wires were connected to the wrong pins on the mobo (they were connected to the reset pins), which is wierd because I connected those wires up as shown in the motherboard manual. I got some signs of life from that, all the fans stayed on after pressing the power key.

Those little jumpers are such a pain in the ass.

 

[mfenn]

Maybe the diagram in the manual was at a different orientation than you expected? Anyway, glad you got it working!