Blank Screen HELP !!!!

Hello, hope all is well? I am wondering if anybody has a solution, as my hard drive switches on fine with all fans spining and NO bleeps! a steady green light appears and then a red light just after. After a short time the red light will then turn off again just leaving the green. My monitor will remain blank with a message 'Power saver mode' as if there is no conection between the monitor and the hard drive. This also occurs with my mouse the red laser does not appear. I have bought a brand new motherboard (exact one) and monitor, and there still seems to be no luck. I am very lost into what to do now any suggestions would be appreciated.

Many Thanks!