Motherboard/processor problem

[hybrid77]

hi, im new here & not sure if im in the right place but here goes....

i've had this pc setup for 3 years working perfectly, about a month ago i removed the video card (sapphire hd4870 512mb) to use in another computer. so i didnt power up this pc for a month & just yesterday i tried turning it on using the onboard video card and the asus splash screen was all distorted and frozen. i turned it off and unpluged all unnecessary hardware then powered up again and got a black screen (monitor light flashing-no video). i then tried putting the hd4870 back in the computer thinking maybe its a problem with the onboard graphics card but no change( black screen) & 3 lights on the video card started flashing which ive never seen before. i also tried 2 different power supplies. ive noticed in a lot of cases its just a matter of an adapter or plug not properly seated, i tried my best to make sure everything was connected properly. so in the end i just have the power supply connected to the mother board with 2gb ram & using the onboard video, i tried with & without bothe the harddrive and dvdrom... no change.

specs...

processor: AMD Phenom II x2 - 3.1ghz
motherboard: Asus M3A78-CM
memory: kingston 2gb DDR2
power supply: Corsair vx 450w
dvdrom: LG
harddrive: western digital 320gb

i posted in the motherboard section because it feels like thats the problem but i really hope not.
if theres something obvious im not seeing i'd appreciate any suggestions, thanks a bunch.

 

[the great randini]

take the ram out and reseat them

 

[hybrid77]

hi randini, thanks for the reply. theres just 1 stick, kingston 2GB DDr2. i took it out and tried to reseat in all 4 slots. no luck. its a new stick, just bought it about a month ago so im hoping its not defective or fried. i have some other DDR2 i could try if you think it might be the ram. correct me if im wrong but even if the ram is defective or nor seated correctly, shouldn't i still see the MB splash screen or hear some beeps telling me theres an issue with the ram?

 

[hybrid77]

normally im pretty good at troubleshooting these problems but i just cant figure this out. i guess i have to assume the motherboard and/or processor might have died for no reason. anyway thanks to whoever took the time to look at this problem.