My PowerSupply burned out Twice!!!

Hi. Anyone's good at electronics? I've just burned out my sec. 300w. PowerSupply in 5 months and i'm real p****d. First time it happened was "under normal circumstances", eg. no overclocking, Intel Celeron CPU running att default(433mhz)no foolin around with core settings and so on. All of a sudden it just died(smelling like a bombed out building or something). Sec time(today), the same thing!! Ok,this time i did upgraded to a PIII 1GHZ CPU running at 133mhz on my old ABIT BH6 66mhz FSB board now running at133 FSB but that can be done..and i did it. Also adjusted the corevoltage to 1.95 for the PIII which is suppose to be cool(?). Since it happened without no overclocking (1:st time) i'm really confused, what seem to be the problem?? I simply can't figure it out. Any suggestions anyone? Will appreciate it!
My Hardware gear is: ABIT BH6/PIII 1GHZ 133/512MB PC133 RAM/
Western Digital HD/win98

Thanks

mrOne