I have an old 450 Pentium III, 12GB hard drive, 256 MB ram, Windows 98. When I turn it on, nothing happens. Just a beeping sound from the internal speaker. Can anyone tell me what kind of problem I have here?

Is there a pattern to the beep?

You may need to check on the motherboard and determine what type of BIOS the board contains. That will give us a handle on the beep code you are experienceing...

It's an Azza motherboard. Don't know the BIOS version. The beeping sound is a consistent medium pitch. Beeps are about 1 second apart and do not change. They will not stop unless the power is shut off.

There are a number of different things that could be wrong and most of them are not good. I would start by opening the case and making sure the dust is blown out and all connections are solid. While in there, write down any numbers or words you find written on the motherboard and maybe anywhere else. Try the computer again and see if you get any further. If not, post back here with as much info as possible, including what you wrote down and any other info you have about the computer, such as brand name.

You could use a copy of my diagnostic charts.
Send me a PM requesting them and giving an email address to send them to.

Here’s one route through them related to your case:

START UP
1. Is the PC dead? No.
2. Did POST appear to run? No?
3. Were there any audible beeps? Yes. [Then you were mistaken, POST did run and the beeps were it's response]
4. Is the Monitor Display correct? No? [There is no display of white characters on a black background]
5. You have a DISPLAY problem.

DISPLAY
1. There is no image displayed on the Monitor.
1a. Is the screen dark or does the monitor appear dead? If so, is the mains lead ok? If it is, the monitor is faulty. If it isn’t replace it and re-test the system.
1b. Is the screen lit up or is the monitor obviously not dead but there is no image being produced by a signal supplied by the video card? If so, is the signal lead ok? If it’s not then replace it and re-test. If it is ok, then the video adaptor and/or system board are/is faulty.

The above makes basic assumptions, such as that the connections are properly made [plugs properly in the sockets, video card making connection] and power is being supplied from the mains to the monitor lead etc.