Re: Optiplex 755 only turns on through power supply button, no video output.

I have gone thru these steps on optiplex 755 and always the same sounds.  6 buzzes: 

1: 3 second buzz followed by same length pause, then

2: 3 second buzz, then immediately,

3. another 3 second buzz, then immediately,

4. another 3 second buzz, then a normal 2-3 second pause

5. another 3 second buzz, and quickly after

6. another 3 second buzz.

That sound familiar?

Any help appreciated!