System not posting

[buschman31]

I have a system that i had swapped out a abit kg7 mobo for a ecs K7s5a pro. installed is 1 gig stick of 2100 with a duron 1ghz in a enlight case(300 psw). that problem is that when the abit board was installed it did boot but very slowly. when i had added what devices-cd and optical drives- it would not boot. then i traded the abit for a ecs board. now the ecs board won't boot up at all. the vid card i was using is a vanta 16mb. i may have to check on that. i'm thinking that its the cpu but i'm not sure. like to get some help before turning this over to the local computer shop or just sell of the mobo & cpu and just get newer combo rig.