My PC had an unknown problem

i want to ask how can i fix my problem
mobo:MSI-MS7507
ram:2GB 2x1gb
cpu:dual core e5700 3ghz overclocked 3.3ghz
gpu:8400gs overclocked to 753mhz 1850 shader and 400mhz ram

how to fix this problem : i plug the power cable and click the power button but the button doesnt has light like normal pc and the screen dosent display anything and the keyboard dosent show light like normal but the dvd drive and floppy drive have light mean it working and has power and also the mouse it show light like normal. i dont know what the problem so i have tried : use my old processor celeron 1.8 ghz but still dont work and the processor both got heat ive tried to boot without heatsink and i have tried to use default gpu still dont work and i have tried to boot without harddisk and what happened when i boot without harddisk is still the same dosent show anything on screen. and i have also tried to remove 1gb of ram and just use 1gb of ram to boot ( this is the normal problem) but it dosent boot

What happened is i'am playing minecraft and suddenly it apear a blue screen and shutdown so i switch off the power and when i start it do like this so what is the solution?
 
Unplug PSU and pull the battery out of the board for 30 seconds to reset CMOS....reinstall battery, plug PSU back in and boot. Let me know what happens.
 
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