Motherboard not working with memeory

Hi,
I am building a new system. I inserted my graphics card and it did not work because whenever I turned the system on, it just flashed and nothing else happened. After this happened there is now no signal to the monitor from the mother board.
Do you think the graphics card could have short circuted my motherboard (it was working before I inserted the graphics card) and how could I test this. I also think that maybe it is not the motherboard but my memory. How could I test if my memory is working. Please help I am really desperate. I have no money left for expensive technical help and have to figure it out myself somehow.
Thanks

Eddie