There could be several causes to your display issue. Here are the most common:
1. Bad or misconfigured RAM
2. Bad or misconfigured GPU
3. Electrical short
4. Bad PSU
5. Bad CPU
6. Bad mobo
Start eliminating possibilities by using the no boot/no display troubleshooting guide (link in my signature).
If the problem persists, post back with the troubleshooting guide as a template.