new process - pc wont boot up

i have a abit kt7a raid 1.3 with 512mb and a duron 900

i replaced the cpu with a athlon 2400 but when i switched on the hdd light stayed on and the monitor stayed blank - i left i for about a minute but nothing

i then replaced the old duron 900 and it worked but very very slowly. cpu usage was nearly 100% for a long time and the hdd light stayed on

any ideas please

i know this is a bit like some other threads but not exactly the same

pete

sorry about the misleading info above - my son has informed me that the pc was slow immediately before i did the upgrade. i have traced this to a faulty memory slot on the mb. i am running ok wit my old duron 900

however, when ireplace that with my new athlon 2400 i still get eveything powering up, lights permanently on on the front panel but no signal to the monitor

pete

Hey whats up everyone, a few weeks a go i turned on my comp and nothing showed on the monoter after replacing a few parts with a bit older parts still the same, So i decided that i would buy new hardware. a new mobo, memory, vid card, but kept my old CPU and still the same results, so im thinking its the CPU or something.

I think what happened is i didnt have it plugged into a power surge and the power went out a few times and it fried somethin.

thanks