A8N-SLI Premium Woes

[ThatGuyInSeattle]

Hello,

I was hoping I could get some sorely needed troubleshooting help with a problem I am having with my ASUS A8N-SLI Premium motherboard.

I'll start by saying that I have 3 of these motherboards in my possession, and they all exhibit the same behavior. I am 100% confident that I do not have a problem with grounding, shorts, etc. and I have concluded that there is nothing wrong with any of my components. I just have something hooked up wrong.

I have plenty of power, a Fortron/Source 550W EPS. It doesn't matter if I load down the supply with all components in the system or just try and hook up the motherboard with no CPU and no memory... bare bones. Here's what happens:

When I apply wall power, the motherboard asserts PS_ON# on the 24-pin ATX EPS supply connector and the system powers up. After about 4 seconds, PS_ON# is released and the power supply shuts down. The standby supplies are still active and functional on the motherboard.

Is the problem simply that the system is in soft off and there is nothing wrong? The power button is not working and I've tried every possible orientation of the panel switch connections (reset, pwrsw, pled, ide_led, etc.) to no avail.

I'm an electrical engineer by trade and, embarrassingly so, I've been wrestling with this problem on and off for weeks now!

If anyone out there has insight into what I may be doing wrong, I'd appreciate the help. This is the first time I've tried to build a desktop system from parts.

Thank you,

Chris

 

[Crashman]

I know you said it isn't shorted anywhere, but that really does sound like you have a standoff in the wrong location grounding a circuit on the back side of the motherboard!

As an electrical engineer you surely know how to start the board without a power switch, it's momentary contact, most of us just use a screwdriver.

If the thing isn't grounded/shorted on the back side, use of the power switch should allow the system to start, and stay running, even if another problem exists that prevents POST. You should have a running, non-functional system if other problems exist.

So get out the screwdriver and jump the PWR_ON pins for, oh, a second, or a bit less. And tell us what behavior the system gives from there.

<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>

 

[ThatGuyInSeattle]

Thank you for getting back to me.

I was thinking about jumpering the PS_ON# on the supply to force it to stay on but decided to call ASUS technical support first. Suprisingly I was able to speak with a human in about 2 minutes.

I actually have 2 motherboard setups right now. One is mounted in the chassis and the other is sitting on a cardboard box. Both exhibit the same behavior which is how I know it's not a shorting problem.

This motherboard has an audio BIOS post, which amuses me :O), and I was trying to use it but had the speaker plugged into the wrong output (subwoofer out instead of line out). ASUS cleared this up for me and then I was able to hear the audio post.

Long story short, with both motherboards stripped down to zero installed components, they both audio post "no cpu installed". When I install the CPU, audio is silent and the supply shuts down after a few seconds.

The third board I was speaking of was the original purchase that I RMA'd.

So, since this has happened on 3 boards, evidence suggests that the CPU is bad (Athalon X2 4800+). ASUS said I should RMA the CPU.

Working with hardware every day, I find it hard to believe that the CPU arrived at my door DOA, but I suppose it's possible. At this point I can't think of anything else to do but exchange the part and try again.

-Chris

 

[Crashman]

Did you have the 4-pin square ATX12v connector plugged into the board?

<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>

 

[ThatGuyInSeattle]

Yes, both the 24-pin and 4-pin supply connectors were plugged in.

-Chris

 

[ThatGuyInSeattle]

So... you're spending your Sunday afternoon correcting someone's spelling on a message board?

Me thinks you need a hobby! :O)