On pressing the power on button, all the fans operate (case/ chasis and cpu), in addition all the relevant lights blink, dvd lights/ power on light etc. Therefore it appears that there is power running through the motherboard. However, the first time I do this it goes through the boot process, tests the RAM successfully etc and reaches the hardware summary screen. Just as windows XP is about to start the blue screen of death appears reading various messages from memory to hard drive errors on different occassions when I power up the PC. However on subsequent occassions, when I power up again or press the reset after the blue screen, it simply shows no display, it does not even beep, the hard disks do not turn on. I have replaced both the motherboard and the graphics card and it is still no better. As the RAM is testing ok when it does test it and this should not prevent the PC not booting up even if it were faulty then it seems to suggest either a CPU or PSU failure. It is also significant to mention that there has recently been a very large storm in my area which caused a modem on my other PC to burn out. In addition, I have not been using any surge protection hardware. Can someone please help me diagnose this confusing problem.