As a preface, I haven't had any issues (hardware) for a while. Last issue was heatsink fan squealing so I swapped hsf and no problems. This was about a month ago.
Okay. Here's what happened: I went to turn on my computer today and before it even hit the post there was one long beep, the lights on my add in 3.5" 42 in 1 card reader, both red and green were on and then the comp shut off. Okay, I thought, it's drizzling out, power could be dodgy and I let it sit for thirty seconds and tried again. Same result. Alright. <Insert appropriate swearing and cussing here, whatever floats your boat> Then, I reach around back while looking and check all cables; check my relatively expensive surge arrester (~$80.) and all wires surge seem fine. One more power button push. Same result. Grrr..... Alright, turn p.s.u. power button off, disconnect all cables, leaving the power cord until last, unplug that and plunk on desktop. I've already brought out both sets of tools and flashlight so I'm good to go.

First, I take a look for too much dust. We're good. Just cleaned it a little while ago. <I do this regularly. Pull everything, dust, reseat properly, boot comp.>

Second, the the visual inspection. Anything "look" wrong? Dodgy connections, wires fallen off, card improperly seated, cable not attached? No.

Third, I try the touch test. Anything too hot that should be warm to hot? Anything cold that should be warm? All seems good.

Fourth, I check all the fans to make sure that they rotate freely, are absent from dust, crude, cat hair on the fan blade leading edges? A little of the hsf.

Fifth, I pull the hsf, clean off the fan blades, check to make sure no dust, cat hair in the heat sink risers/fins and use compressed air to blow out. Nothing comes out.

Sixth, I pull the CPU and check for thermal extremes, there is no scorched metal smell, no visible signs of too high heat. While I had the hsf off, I lightly sand papered the bottom of the heat sink to "even" it out, using a flat block.

Seven, I inspect the board itself and slots for dust, foreign object intrusion/contact. (My case is enclosed with all sides on it and no open panels/slots other than what it is designed to have. Good.

Eight, I pull the chip completely, along with the vid card (no fan, passive cooling), memory (no dust buildup on modules or around mem slots) and check sound card, add in USB hub cards for proper seating. All good.

Nine, I check the ATA/power cable connections to hard drives, main h.d. (OS on C, 8GB, E: 2nd partition 66GB.) ATA cable at h.d. is a little loose but nothing major. I reseat it. I check the second H.D. (Drive 2 and D:\ drive. 128GB.) All good.

Ten, I put it all back together in proper sequence, with the left side cover left off, hit the power button and same shit occurs. Grrrr......

Once again I try, I give the main h.d. a little tap and voila! It boots this time but once it hits the OS it spontaenously reboots. Grrrr once again.

This time, it does a chck disk and sets aside some files. (Xp pro.) It gets to the OS this time and stays there a little longer before rebooting again.

On this occasion, when it goes to chck disk, I hit the enter button on k.b. to make it skip the disc check. Goes into the OS with no troubles.

I then check thru the device manager and no conflicts.

I'm thinking thermal issue with chip or PSU failure since the issue occurs so quickly after starting. Secondary possible problem is the main hard drive is failing. YIKES! Third possible issue, vid card being dodgy. Fourth, USB add in 42 in 1 card messed up in some way.

Any ideas gentlemen? The only new software I added was Thunderbird yesterday which I uninstalled and Eudora, both of which shouldn't affect the boot process.
I am going to run a full a.v. scan, rootkit and the whole works but my feeliing is that it is at a machine/hardware level. Any relevant suggestions about the hardware will be appreciated. Thank-you.

*bump*

Anyone?

"before it even hit the post there was one long beep, the lights on my add in 3.5" 42 in 1 card reader, both red and green were on and then the comp shut off. "
sounds like a power problem to me. i would unplug everything and replug.
is there a fan on the northbridge? if so is it dirty?
how old is the board? maby the onboard battery is going bad.

someware to start mate.

also what bios is it , 1 long beep could be memory

Pappy:
No fan on North Bridge. Board is 7-8 years old. Asus A7V with Via Apollo KT 133 chipset.
One mem module is less than 1 year old. The other is good, I swapped slots with them. Infinity with lifetime warranty.
With the exception of the sound card and PCI USB card, I pulled everything else.
The system is retaing the settings in the BIOS so I suspect it isn't the CrO2 battery.
Award BIOS.

I have cold booted it at least 4 times without issue. It could be a transitory problem.

Thanks for your help, Pappy. Appreciate it.

The only AwardBIOS beep code indicates that a video error has occurred and the BIOS cannot initialize the video screen to display any additional information. This beep code consists of a single long beep followed by two short beeps. Any other beeps are probably a RAM (Random Access Memory) problems.


http://www.phoenix.com/en/Customer+Service...Error+Codes.htm
:-|

Bart your first known problem was a heatsink fan (cpu I assume). As you well know the PC won't boot if it doesn't "see" cpu the fan running. I'd eliminate that possibility first. I'd do a Memtest for sure, to eliminate that. Do you have another PSU to swap out? Also look for leaking or bulging Capacitors around the CPU.

http://www.memtest.org/ ray

Thank you gentlemen for your concern and help. Cheers.