Might need to explain this a little better because you wouldn't be able to tell if the video card or monitor is fine if there isn't a working processor or motherboard and the computer isn't starting up.
When you turn it on, exactly what is happening?
What error message, if any, was present on the BSOD you mentioned?
When booting, do you get to the POST screen?
Are there any beeps?
Also need full specs for your system.