Opening Beep on bootup

This is not an issue but rather a question. For many years I have listened for that first beep when you boot a desktop but never really known what it meant. I mean I know without it the system will not boot up but I as I sit here this morning after repairing a desktop that was failing to have its first beep and failing to boot when that happened as well, and I have never really known the answer (or if I did I forgot). So how about some of the hardware gurus sharing that with me.

This particular custom build was really tough to figure. I physically cleaned out a ton of filth and yet had an occasional fail to boot but it got better. I change the psu and no difference. I replaced the 4 year old hard drive because I felt a drag on response even though the hard drive tests had the drive as fine and the response time got so much better. I replaced the video card and saw no change. I tried system on onboard video and no difference. Then I found one of two Ddr2 ram sticks was actually causing it to fail to boot and since I replaced it, it has worked every time. Odd because the 4 gb ram registered properly but with that 1 stick of ram alone, no beep and no bootup.

I should add 4 year old desktop in a farmhouse, MSI K9N6PGM2-V V.2 GeForce 6100 Socket AM2+ MB, AMD Phenom X4 9600B 2.3Ghz AM2+ OEM CPU , Cooler Master AM2 95w CPU Fan , WD Caviar 500GB Serial ATA HD 7200/16MB/SATA-3G , Sapphire 5450 512 meg video card, Lite ON 24X DVDRW SATA OEM , Logisys 575 watt 24 Pin Psu , Crucial 4096MB PC6400 DDR2 800MHz

 

To some extent to confirm Tony's comment, some motherboards don't have the little beep speaker fitted, so of course no beeps will ever be heard.
However the single beep is usually the signal from the BIOS that POST has been confirmed to be OK and hopefully the next thing to happen will be the operating system will boot up.
However, if a fault is discovered during POST, some BIOS systems will give multiple beeps, and usually in some form of code of long and short beeps, or just a multiple of beeps.

Lots of good info on it all here :-

https://en.wikipedia.org/wiki/Power-on_self-test

Nev.

 

Another thing which can stop the Post Bios Beep is if the intergrated audio controller has been disabled.

 

Thanks everyone I believe that to be the right answer....must have been some fogginess in my brain this morning.

 

Actually its not the right answer if we are supposed to see the P.O.S.T first as I noted this AM the beep is long before I see the first of any post screens.