When faced with a machine that doesn't beep, forget about the video display and work down to a smaller list of parts.
I usually go for the throught of the problem by stripping it down to (unplugging cards and cables) to just the power supply, motherboard, CPU/HSF (HeatSink/Fan) and the speaker. Power up and hope for beeps. No beeps and I'm looking at the 4 possible bad parts.
No memory sticks, not much else in the stripped condition.
While one may state it could be the motherboard, the test has been great to get it down to the point of these four items. The GHz Athlons do have a design problem that move it up higher on the list. This web article along with the VIDEO/MOVIE of what happens when the heatsink falls off, graphically shows the problem -> http://www.tomshardware.com/cpu/20010917/index.html
Since the Athlon self destructed in under one second, it's a prime suspect.
Bob
k, have had computer two years..
Compaq pressario
1.1g athlon proccessor
384 sd ram
250watt power supply
uwave mobo 786 k1
alright, upon startup lights come on, hard drive spins, fan turns on...BUT, no beep, no picture. Checked video card and hard drive in other computer, both fine.
Now thing is it worked then didn't work, then worked. Then it wouldn't work so i took it apart and cleaned. Then it worked. But, alas it does not work again...(time frame about 2 days).
Friends say it's the mobo, but it works sparatically. Please someone help, NEED.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic