Trouble installing new mobo need help.

Ok so recently my gf's computer died and with the help of some friends we deduced that we were pretty sure it was the mobo, anyway i ordered a new one that was same socket just a slightly newer version.

After taking out the old one installing the new and everything i tried turning it on for the first time which resulted in nothing but a black screen but the fans were running all the lights going but no beeps from the motherboard and no sound at all. (this was the same sort of problem we had when it died) So when this happened i tried trouble shooting for a long time and read all the stickys and the 24 step list on toms hardware trying to work it out to no avail, heres what i got in terms of information.

At first try i was using my gfx card, in an attempt to double check that it wasnt the card i used the on board card and took the gfx card out, wat this resulted in was that now when i booted up i would see the boot screen (the motherboard brand name screen with the press del to enter bios etc.) for about 1 second then it would go back to black, but later when i had my gfx card back in the case i was still getting this one second display so it wasnt the card.

After this i took the mobo out of the case and start breadboarding it like in the guide, i started with just her power supply CPU and HSF but still to avail no beeps.

At this point i swapped her PSU for my PSU but still no beeps.

So what im left with is either im guessing its a DOA board or its the CPU but i cant test the CPU cause my CPU doesnt fit her socket.

So i was wondering if maybe with the little information i was able to provide and the fact that its actually showing me the boot screen for all of 1 second one of you may be able to deduce which one of the 2 would be causing the problem.

ASUSTek M4A785-M AMD is the board i got.

I forget what the cpu is i blieve its a mamba or oasis or something im not 100% sure, i kno its a old dual core amd processor