Old Pentium 3 doesn't work, how to fix this problem?

I need to find out what is wrong with this problem. The computer is Pentium 3, when I boot it up, the screen is blank with no beeps. The hard drive spins, and there is power to every device. I checked all the connections, changed the video card, the ram is 256 MB DIMM and 64 MB DIMM. I dunno what the problem is.Old Pentium 3 doesn't work, how to fix this problem?
No beeps means the BIOS crashes before, or it's not running, (or the speaker is unplugged, lol). It's either the CPU, motherboard or RAM. Try with only 1 RAM stick. Try clearing the CMOS. Check if the mobo has ';leaky'; capacitors.



It's easier to test with all device data and power cables unplugged. I've seen motherboards that won't turn on because of an upside-down IDE cable.Old Pentium 3 doesn't work, how to fix this problem?
Disconnect the flatcable going to the harddisk and the floppy drive. Either one is connected the wrong way around (pin1 on the wrong side).
Then, it's either the power supply unit, or the motherboard. The hard drive spins, but the MoBO may not be getting full power.



Test the power supply in another PC. If it works, all that's left is the MoBo.
Different RAM sizes? and also is the RAM compatible with the motherboard?