infuriating problem with a M2N-E Asus mobo...

[roddenberry]

Aargh. Just finished building a great little PC using a M2N-E mobo by Asus. I had the manual so setup and install went like a charm. Put a 660w power supply so I can power-up my Nvidia GeForce 8800 card (it has the 6-pin PS connector).

So everything went well and I installed XP, all the drivers and the service packs and updates. 100% good, speedy little PC, awesome video performance. I am happy.

This morning, I start-up the PC... it stays on for 3 seconds and then shuts down. Tried again and again... same thing. I thought maybe a bad BIOS battery (some Macs behave like that when the battery is dying). So I changed the battery with a new one... Still shuts down after 3 seconds.

Then I tried booting while holding the reset button. It stays on as long as I keep my finger on the button. As soon as I release it, it shuts down. Frustration...

Just wondered if anyone experienced that particular problem with a M2N-E or other Asus mobo?

I tried to disconnect everything, including the video card and HD, and it still shuts down after 3 seconds. What I don't understand is that it ran fine for several days without a hitch.

Thank you in advance for any insight or any anecdotes about this evil mobo...

Robert

[Karlsweldt]

Lots of helpful tips in this link to "troubleshooting" here on the Forum..
http://www.motherboards.org/forums/view ... hp?t=39873

But a few quick checks.. ensure the CPU and its cooling fan/heatsink are securely mated. It can take less than 5 seconds for the CPU thermal cut-offs to activate, with high temperatures! And check the thermal limits in the BIOS for CPU cut-off. Some CPU models do run hot, so set the cut-off temp around 75°C to 80°C, which would be about average. And ensure all power sockets mate with power leads from the PSU. Same if using a high-end video card, they require a lead set.
Then there is that nasty "bad caps" syndrome.. where capacitors go bad, and cause all sorts of problems. If any show domed tops, lean excessively or have signs of leakage, they are bad. More info at www.badcaps.net/ .

[roddenberry]

Thank you for your reply. Ugh, sorry. I intended to post in troubleshooting, but I got logged-out and when I logged in again, I had a brain fart.

Checked all the caps and they are fine. I replaced so many caps over the years on mac G5 and intel mobos that I lost count… always about a 50/50 chance that it works or not.

The CPU is perfectly seated, and when the machine was working, the front-panel temp probe was reading normal temp, same for the VGA and HD temp. probes.

The CPU fan is a PWM model, and all other chassis fan are the 3-pin version that were manually optimized for quiet operation.

I tried another new Power Supply and same thing. So after all the tests and replacing and disconnecting components, the only culprit possible seems to be the mobo. I am so disappointed, this was just about the best little PC I ever built, and I only got to play with it for a few days.

Robert

[Karlsweldt]

I always have a POST diagnostics card at hand.. and it is an excellent tool for diagnosing motherboard problems that don't show up easily. Not expensive to own, and there are models that range into the hundreds of dollars.. for the 'pro' tech. But for common use, under $40.00 USD would be a sound investment. It displays a two-character code for each POST process. Any character set that "hangs" can be referenced for the situation.
But do one last test.. the "PG" or "power good" signal from the PSU. It should be at +5 volts after the load stabilizes, and then timing circuits become active. If too low, then no activity. Could be a mobo circuit problem, or the PSU is having problems.
Recommended for testing only, if that +5 volt "PG" signal is low.. a 47-ohm 1/2 watt resistor bridged between a +5 volt source and the "PG" lead. If you now have life signs, check other voltage levels.
If indeed a fault on the mobo, not much can be done.
But still, capacitors do go bad internally, and only after some time do they exhibit outward signs. Hope your problem is not serious.

[evasive]

roddenberry, can you please report the make and series of the caps on your board? Some can fail without any visible signs. If there's KZG series on their (in particular near the CPU) there's a good chance they have gone.

[bdub]

just wondering if you clear the cmos, and put the cpu fan control on full speed... maybe that changes things?