Single (Microwave Style) Beep During Login Screen

[BenEndeem]

When I switched my iMac on this morning, I went to the other side of the room to gather some paperwork and as I was doing so, I heard a microwave-like beep come on during the user login screen. It was only a fraction of a second long and didn't repeat, but it has concerned me.

I know that these iMacs beep for RAM issues, so I tested the RAM firstly by trying to utilize all of the RAM which seemed successful, then with TechTool Deluxe and finally with Memtest, both of the latter are showing that RAM is okay, but I will continue testing throughout the day in different modes and so on.

My question is, could this be anything serious? What could the single beep mean; just a glitch or something worse.

Any help would be greatly appreciated, thank you.

 

[BlueRevolution]

http://support.apple.com/kb/HT1547

A single beep means that no memory is installed, but obviously it's working. As well, the diagnostic beep should only happen when the computer first turns on.

Does it happen every time? If it only happened once, I would just forget about it.

 

[BenEndeem]

I phoned Apple Care and apparently if you hold the power button for too long it can cause a short beep during login, to quote the guy "if it's on the login screen and not the startup, it definitely isn't a RAM issue". Still, I'm about to go and test that theory and see if it does it again while I'm at it.

Thanks for the reply too.