I'm very sad, this system means a lot to me.
It would sometimes power on for a couple of seconds and then go off. I used to only take a couple of goes, but it got worse and worse until now it powers off after a couple seconds every single time. If it did come on, it booted fine.
I only have the PSU, speaker and CPU and cooler installed at the moment and it does the same, no beeps. For 15 years this PC has not shown any signs of wear at all.
The weird thing is, what I used to have to do when it was getting bad, was I noticed the colder the system was, the harder it was to start. It got to the point where I had to take off the side and place a heater to it for 5 mins, and it would start fine. Like a car not starting cold.
2001 LEC Science (Optima clone)
Asus P4B-M motherboard
Intel Pentium 4 1.50 GHz
2x256 MB RAM
Gigabyte RIVA TNT2 M64 graphics
Seagate U-Series 20 GB IDE HDD
3.5" Floppy drive
Delta 250W PSU