Orignally working computer won't post

[jclaydon]

Ok I am completely at my wits end.

I had a computer made from an ASUS commando motherboard, 2 1g corsair memory modules, an ATI 3850HD video card and a server power supply and an intel celeron 3mhz processor.

It worked perfectly fine for a couple of months, then i took off the case door to clean out the build up of dust. I used a small amount of compressed air.

Now it won't even post. When I press the power switch the fans all come on, but the HD light comes and stays on, even if the hard drives aren't connected to the motherboard at all.

any suggestions?

-James

[zburns]

Not sure I can help but I can try. You mention hard drives in the plural, meaning you have more than one. Right? For your computer to boot up you must have the hard drive with your installed OS that it boots from connected to the mother board; that is unless you are booting from a floppy or CD, which I doubt.

The reason a hard drive (led, I assume) lights up would be that the power supply is still connected to the hard drive but your SATA or PATA(IDE) cable from the hard drive to the motherboard is not connected. If you have more than one hard drive you must know which one your OS is installed on!! A hard drive with the OS on it must be connected to the mobo in order for the computer to boot.

If you are using a "server" power supply, I assume its connectors are compatible through some "computer standard" if they would plug into your hard drives and mobo. This means the connectors on your "server" psu must be exactly the same, from the factory, no alterations, etc., as the connectors on an Earthwatts PSU in an Antec Sonata III case, for example. All this means is that the server PSU external wires and connectors were in no way altered. (I am saying the same thing different ways so that it is clear what I am getting at.)

Give me some feedback on the above while I check out the possibilities on your use of compressed air.

[zburns]

I am back with some compressed air comments. Here is a link describing a procedure for using compressed air:http://www.ehow.com/how_3664_clean-computers-insides.html. These procedures make sense. The one that says leave the computer plugged into the surge suppressor needs some explaining. Doing this probably maintains the ground connection thru the power cords, but as long as the ON / OFF switch on the surge suppressor is off, no live power is in the computer cabinet.

Some of these procedures can be vital to not causing a problem, you did not previously have, for example, anti static protection, ie. ground yourself to your computer cabinet, the cabinet needs also to be grounded but not plugged into live voltage source (see the comment above and on the link about "plugging into the surge suppressor" -- just be sure the surge suppressor is turned off) -- did you do this? Did you use a brush inside the cabinet and "brush off the various circuit boards". Either one of these "actions" done without correct anti static procedure being followed could (not saying it happened) damage a circuit board component.

[jclaydon]

thanks for the suggestions. But I had disconnected the drive completely from the PATA interface including the cable. so the drive led shouldn't light up at all.

Besides the POST procedure is what happens before any I/O devices are accessed. *you know that beep noise the computer makes before anything is loaded*

The error message I get on the LCD screen says "Init CPU" which is the original message I got when I first started having problems the first time and I replaced the power supply to fix it, but I'm certain that it isn't the power supply this time.

My guess its either the CPU or the Motherboard is faulty, but I don't have the skill or the diagnostic tools to figure out which one it is.

[zburns]

You cannot have a hard drive with the LED lit, and not have a cable plugged into the back of the hard drive supplying the power that causes the LED to light up, but that seems to be what you are saying. If the hard drive LED does come on with the P
ATA cable disconnected, there has to be a four pin connector from the PSU plugged into the back of the drive.

The back of your hard drive should have three separate connectors. The first is a long connector for your PATA cable. Next there is a connector for "jumpers" (no cable connects here). Next there should be a 4 pin connector for the power; the connector that goes here is from the power supply. If this is not the configuration you have on the back of the hard drive, tell me what you do have in the way of connectors. If you have a four pin connector with a cable and four pin plug from the power supply, you might try unpluging it and see if the light goes out.

If you only have the one PATA connector, give me the Hard Drive mfg and part number off the hard drive.

Please look at the power supply and get a manufacturers name and part number off the label on the psu. If there is more than one number, give me all of them.

I will look up your mobo and Init CPU and try to make some sense of that. The word post is more recognizable when it is all caps POST; sorry it just did not catch my attention. More focused on the PSU being from a server. Blowing the comp air in seems to be the trigger, but I thought we would start with the PSU and work up from there.

I am trying to find out what voltage and current pinouts there are coming from the PSU. Since you say it is from a server, I cannot tell it is compatible or not. The mfg and part number should help.

[zburns]

Assuming you know for a fact that your "server" power supply is compatible and not a "contributor" to your problem, you then tackle the "dead" mobo issue. I know that "assuming" the PSU may be a problem is a stretch, you do indicate you have already replaced it once, and it is a "server" power supply that you presently have. I would not go further until I know that the existing server psu is definitely compatible.

Assuming it is compatible and works properly, then I see two possibilities for the present mobo condition. Your use of compressed air caused one of two things to happen: (1) The compressed air was conductive due to a static charge transfer from you as it was used, and the BIOS was corrupted; therefore, POST will not occur. Assuming no real component damage occured, you could FLASH the BIOS and the mobo might then perform ok.
OR (2) the conductive compressed air not only corrupted the BIOS but caused component damage. You would have not choice then but to get the mobo repaired.

Regarding the "flashing the bios", another forum member, WM, Ricky Tick or others with more build experience should verify or correct what I am saying. Since I have never done it, I am only repeating what I have read, particularly Rob's book.

[jclaydon]

Just for the record I took the motherboard back to the place where they got it and they said it was indeed faulty.


So apparently something from the spray got cold enough to make a microfracture in the pathways to short out one pin.

guess i was holding the nozzle too close.

live and learn

-James