computer post problem

I have been computer for years and I have had problems in the past, but this one is driving me crazy. Can anyone help with some solid suggestions. I have all new components in this new computer I just built it won't post. I have change the processor from a duron 800mhz with a 733, changed video cards change and tried different combinations of memory. When I turn it on everything comes on all the lights in the front of the case, all the fans work, I even changed from a new 350watt power supply to a 400watt, and change monitors. The screens are blank, no matter what I do it won't beep to post. Help help.
Thanks for any suggestions what will work.

larry webb

i had a similar problem (or so i thought). it was embarassing too. i put in my vid card first then the rest of the cards, i forgot to put in one of the supporting screws in the middle of the mb so it was flexible. i didn't notice, but the end of the vid card poped out of the agp slot. i'm not saying that this specificly is your problem...but it never hurts to double check.

no vestige of a beginning, no prospect of an end, when we all disintegrate, it'll all happen again.