New motherboard, still no POST

[Kalmah]

Ok, here's what I got.

1: 3.37
2: 3.37
4: 5.19
6: 5.19
9: 5.02
10: 12.06
11: 3.37
12: -8.73
18: -4.97
19: 5.19
20: 5.19

Pin 12 seems to be very far off.

 

[Navid]

What did you measure on pin 8?

 

[Kalmah]

pin 8 is 5.18

I didn't measure it at first.. thought it was a ground.

 

[Navid]

What is the voltage on the wires on the 4-pin CPU connector? It must have 2 12V wires on it.

 

[Kalmah]

Originally posted by: Navid
What is the voltage on the wires on the 4-pin CPU connector? It must have 2 12V wires on it.

Yeah, they both read 12.06 on the cpu 4 pin connector.

 

[Navid]

OK,

Power down the PSU by removing the short between Green and Black.
Flip the switch at the back.

Measure the resistance between the two connectors of the power switch on the case. It gets connected to the motherboard with a connector that is probably labeled "Power".

So, you need to change the setting on your meter to read resistance and connect each one of its cables to one of the two connectors.

We are doing this measurement on a bare case with no PSU.

The resistance should be very high. While you are measuring the resistance, if you press the power switch on the case, the resistance should drop to 0. it may read something between 0 to 1 Ohm.

I will be back in about an hour.

If the power switch measures OK, you should place the motherboard on a non-conductive surface like its antistatic bag on a table and connect the CPU with the cooler, RAM, graphics card, PSU keyboard and mouse only. Nothing else. You also need a speaker.
Connect the monitor and power up and listen for beeps or diagnostic messages.

The fan should not spin until you short the two power pins on the motherboard where you connect the power connector from the case.

 

[Kalmah]

ok, I don't know if you're going to notice this before you get back. I just want to try to confirm what you said as some parts seem unclear to me.

I am to remove EVERYTHING from the case? (mobo, psu, disc drives, hard drives...)

Then measure the connectors behind the power on/off switch? (I can't measure the end of the wire that's connect to it that connects to the mobo?)

I'll start by just measuring as is.. if I don't hear from you after I've done that I'll continue to strip the case so I can do it with it empty.

By the way, I don't know if I mentioned this before.. I did try powering it up with the mobo setting ontop of the antistatic bag ontop of a book outside of the case with the same results. (psu and everything was still in the case, just the mobo wasn't) The only thing connected to it when I did that was the cpu, memory, hard drive and psu.

I really appreciate all your help.

EDIT: I forgot to mention that I've tried this system in 2 different cases; 2 different power on/off switches. It's very difficult to get behind the power button in my case. There is a non-removable cage in front of it. So I've decided to hold off on that for now unless when you reply you say it is very important. I hope you understand.

Let me give some more detail or bring up some other possible issues I think could be causing a problem.

When the system booted up(after several times of not working) I can't remember the previous thing that I did prior to it working. But I do know that I plugged in the floppy and cd drive to the power and motherboard after it was working(and before it stopped working). I also plugged in the front USB panel to the USB56 connector on the mobo between the time that it worked and the time that it stopped working. (I can't figure out the difference between USB56 and USB78?) I've read stories about connecting the USB wrong frying mobo.

But.... it wasn't working to begin with anyways. So I'm guessing it has nothing to do with anything.

It almost seems that the cpu is left as the final culprit.

I guess that's all that I know of.

I'm looking forward to your reply. Thanks again.

 

[Navid]

I just wanted to make sure that the power switch was functional. You connect that switch to the motherboard with a cable that is a part of the case. It is usually bunched up with the hard drive LED, power on LED, and reset switch cable. I just wanted you to measure the resistance between the two ends of that cable. Nothing to dismantle or remove other than pulling off the "Power" connector from the motherboard.

You said that you have tried two motherboards.
What are those motherboards (brands and models)?

 

[Kalmah]

I'm not sure that I follow you. I checked the ohms on the connector on the motherboard that the power button plugs into. It reads 0. Tried touching the probes to the end of the wire that plugs into those connectors but can't make a connection.

The old motherboard is an Asus P4c800 Deluxe.
The new motherboard is an Asus P4s800d-x
Processor is a p4 3.0ghz socket 478
RAM is Corsair twinX extreme pc3200 512x2
PSU is Coolmax ct-550 psu link

The connectors from the front panel(hd light, power button, reset button...) are all plugged so that the black wire is connected with the indicated ground connector.

Thanks again.

 

[Navid]

Originally posted by: Kalmah
I'm not sure that I follow you. I checked the ohms on the connector on the motherboard that the power button plugs into. It reads 0.

No, that's not what I meant.

Tried touching the probes to the end of the wire that plugs into those connectors but can't make a connection.

Yes, that's what I wanted you to measure. Can you insert two metallic pins into it and then make the measurement on the pins sticking out?[/quote]

 

[Kalmah]

I don't believe that I have a single pin in the entire house. I just tried with some very tiny paperclips but they seem too big. I got them to stay, but I couldn't get any reading off them. I'm afraid I might mess up the connectors if I jam them in further.

I'll continue to look for some pins while I'm waiting for your reply.

 

[Navid]

Let's skip that measurement for now.

Put the motherboard on a non-conductive surface and have the CPU with its cooler connected. Connect the CPU fan connector to the motherboard.
Connect the PSU 20-pin and 4 pin connectors to the motherboard.
Add your graphics card and connect to the monitor.
Add one stick of RAM.

Do not add ANYTHING else! Not even the case front connectors. Nothing!

Now, plug in the PSU and flip the switch at the back of the PSU on. Only the green LED on the motherboard should turn on. If the CPU fan starts spinning, power down and report back.

Make sure you only connect those items I mentioned and nothing else.

 

[Kalmah]

Ok, just did it. The CPU fan runs when I turn the psu on.

 

[Navid]

This is your motherboard, right?
http://dlsvr01.asus.com/pub/ASUS/mb/sock478/p4s800d-x/e1753_p4s800d-x.pdf

On page 28 (the last page of chapter 1), it shows "System panel connector".
You have not connected anything to that connectr, right?

 

[Kalmah]

No, there is nothing plugged into that.

 

[Navid]

I wouldn't say that it is the CPU.
Unfortunately, I am out of ideas!

I suggest that you start a new thread in the General Hardware forum.
I will be monitoring it.
If that one does not get anywhere, I will start sending private messages to a few guys who may have some ideas.

Please do not lose hope and do not think that it is the CPU. At least, not yet!

 

[Kalmah]

Thanks a million for all your help. I will do as you suggested.

This is just the most strange thing I've ever seen.

The cpu fan isn't suppose to run when the psu is turned on is it? (it does with both mobos)
But.. when I tried a different psu when I was at best buy, that didn't happen. I had to hit the front power button to turn them on. (but still no signal to monitor)

It seems like that would be enough to say that it is the psu... but why the hell didn't it work with the other one!!?? aaahhhhh

Bah, I think you've heard enough of it. heheh

Well, it looks like socket 478 processors are fairly cheap compared to some newer ones.
But right now I'm in the middle of switching jobs and have holidays coming soon; I'm short on cash. My biggest fear is to find out that their wasn't a problem with my original motherboard in the first place. I think I have 30 days before I can't return the new one anymore. I wish I just had all the parts so that I could try other ones. (cpu and psu specifically)

Anyways, thanks again. I'll probably be actively working on this here on anandtech for a little while.

 

[Navid]

I agree with you and do suspect the PSU.

There is a lot more traffic on the General Hardware forum and there are a few guys who frequent it who are great and I will PM them if they themselves do not reply.