Can bad memory really cause this much damage?

[quinnsi]

I recently bought 4GB of RAM from Crucial for my 8 Core 2008 Mac Pro. After mounting the ram, and turning the power back on, the screen remained blank and the external speakers wouldn't work. I still hear the chime from the internal speakers, as well as the fan on my graphics card (8800GT) going at full speed.

I tried removing the new RAM, and many other combinations, but now neither the monitor or the external speakers will work. However, the keyboard still does work, since when I hit the volume buttons, I hear the chirp from the internal speakers.

Any thoughts? Could replacing the RAM really cause this kind of problem? If so, is there anything I can do?

Thanks in advance everyone!