I have a desk top in my house. when ever i plug in and switch on main power, immediately my system starts. no need to switch on cpu power button. what is the problem and how can i rectify this?
Maybe you can change that through a BIOS option, but there are so many and they vary depending on the system, you'll have to check your motherboard manual. Go to the part where they describe the BIOS menus and options and I would look for something like "Power On" options. There's usually an option to turn on the PC automatically when it recovers from a power failure, this could be it.
Is there any chance the power button is jammed? Also try taking out the CMOS battery, I recall some motherboards have a function that allows the computer to turn on by itself. I myself know my computer turns on by itself when the power gets cut and once back it turns on. Perhaps there are some significant power fluctuations that may seem like a brief power cut to the computer? Try hooking up to another power source and see if you can swap the power supply and see if the issue persists.
Edit: Darn it, took too long to reply to that, MC_K7 responded in time. Anyways call an excorcist, the computer may be possessed