My computer has been freezing shortly after start up and then it wouldn't even boot up. It just sat at a black screen with a flashing underscore. Someone suggested getting a new motherboard. I just recieved my new motherboard today and so I installed it. After connecting everything I went to start it and nothing happened. No fans started or anything. I have checked all of the internal connections about 5 times and they are all correct. Can someone help me!!!