Question How can I test my cpu,motherboard,ram and battery?

[Psh Marais]

1.Why is it when I want to start loading my OS,everything stops to work,PC totally shuts down(IBM Rev:2.4 mPG A478B)?
2.When I plug my box in to the main,its starts running without me switching it on at the box.(450W PSU)
3.How will I know if my motherboard is in working condition?

 

[Mockingjason]

1.Why is it when I want to start loading my OS,everything stops to work,PC totally shuts down(IBM Rev:2.4 mPG A478B)?
2.When I plug my box in to the main,its starts running without me switching it on at the box.(450W PSU)
3.How will I know if my motherboard is in working condition?

please give a little more detail about what's happening