Some problems I have been having lately, namely, this morning. I just got the components for my new system yesterday, put it together, using the 300W power supply from my old system that has working since last Christmas and it worked from around 8:30 till around 2AM, when it made an odd sound and turned off. It was late, so I went to bed, this mornin' I turned it on, it made a horrible popping sound and I smelled burned electrode. Took it apart and the smell is coming from the power supply. What happened?

Stats:
L&C 300W ps (blew up)
Gigabyte GA-7DXE motherboard
Athlon XP 2100+
Seagate 20Gb ATA hd
Standard Floppy
Standard CD Drive
ThermalTake Volcano7 CPU heatsink
Leadtek Gf4 128DDR TI3600 video card
512 DDR Ram
Creative Labs Sound Card
Motorola 56K NetODragon Modem

I dont think it was heat because the side panel was off and my window was open. It was(is) cold. (Northern California)