unknown POST beep

[threedots]

I have an Asus P4B266 MOBO that ran fine for about three weeks. One day it began failing its POST and is emitting a tone I cannot identify and have not heard before.

The sound is best described as a continual "up-and-down", or "rising and falling" tone. This will continue until I shut off power at the power supply switch.

I began my investigation by pulling components; first one-by-one, then groups, until I had only the CPU, fan, and RAM. I checked the RAM in another working system and found it to be good.

I did the usual research into POST tones and looked for the Asus BIOS tone charts, but could not find this tone listed.

A system builder I know suggested dead RAM, which checked out fine, or a dead or malfunctioning PS, which appears to be OK. Now I'm stumped...

Is this a:

a.) CPU failure problem?
b.) MOBO probelm (and if so, has anyone heard this before?)

Since all components are still under warranty, I'd like to identify the problem as soon as possible. Any ideas?

Thanks for any feedback,

Mark (Threedots)


System Specs:

BIOS: set on most defaults, tweaks on the AGP data rate (to 256), antivirus turned off, and PNP turned on. This is a very straightforward build. No overclocking, CPU speed left on auto.

Asus P4B266 MOBO
Intel Pentium 1.7GHz CPU with Intel heat sink and fan (factory pack)
GeForce MMX 4X AGP video
256MB DDR 2100 RAM
D-Link 10/100 NIC
USB 1.1 ports connected to front chassis add-on device

 

[gargouille]

You still don't list the mfr. of the BIOS...who is it?

 

[gargouille]

It's possible (taking for granted your monitoring section of the BIOS is not set to alarm at a low temp) that the Winbond temp sensor is bad (IF there is one), sending either an overtemp or bad CPU tone.
I've heard it before from boards that were having temp problems (CPU cooler/fan completely gunked with dust)...altho I don't remember if they were Asus...seems they were. Either that or the CPU fan may be turning too slow to satisfy the system.
When you took the box apart and checked the CPU/cooler, was this the case?
It's the best air cleaner you have in the house, and you'll find a major collection of the airborne particulates there!
I think you're gonna' need another processor to test it.