What is my problem??

Awhile back I fryed a mobo and bought a new one when I tryed to start up the system afterwards everying would work but nothing would show on the screen (tryed different video card,monitor,etc). I bought another mobo and it all worked fine. Some time down the line I wanted to upgrade my mobo because this one didnt have an AGP slot and I had bought a ti200. Same problem when I tryed to start up nothing would show on the screen. Alittle later I bought another mobo and same problem. Yesterday I bought a xp 2400+,soyo kt333 dragon ultra plat.,512 pc2100 266,and a powmax 500w psu (junk fryed already). Anyway after I got the system all set up and tryed to run it I got the same problem nothing would show on the screen but everything else seemed to work fine. Keep in mind after all this stuff dont work or whatever I can take the "old stuff" and pop it right back in the case,start up and it all works fine. What seems to be my problem?

not trying to sound mean, but it seems to me you have no idea what you're doing. stop wasting your money and ruining components. do a little reading and progressively work your way into building your ideal system. it's not about just jamming parts into a case then pressing the power button.

here's a good place to start:

http://www.tomshardware.com/howto/20020904/index.html

http://www.tomshardware.com/howto/20020918/index.html

good luck.

Umm i do know what im doing perhaps i just didnt want to write an essay about my problems. Thats why it may seem that i just cram it all in and go.