I have a old pentium 4 2.4 GHz machine with D845gebv2 motherboard and ATX cabinet. The system was working well up until recently. Few days back when I switched on my UPS, the machine started directly even without myself switching on the power button on the ATX cabinet.
Due to this I hope that my LAN card is spoilled.
I tried all the possibilities to find out whether the problem is with my UPS by directly connecting the machine to power supply. Even in this case as well the machine starts directly.
I have opened the cabinet and found that all the cards were attached properly.
If some one could please help me resolve this issue, it will be greatly appreciated.
This could just be a BIOS setting that has somehow changed (perhaps the CMOS RAM backup battery has run out, which is entirely possible on a fairly old board especially if the mains supply is turned off when it's not in use).
Go into BIOS Setup (press F2 while the system memory test is in progress, before your OS starts loading) and navigate to the "Power" screen. Check the "After power failure" option - if it says "Power on" then this is what is causing your system to start up automatically when you apply mains power. Change it to "Stay off" and the system should, well, stay off when power is applied.
If the CMOS battery is flat, then you may of course find that this setting doesn't get saved. If it is set to "Last state" (which is the default) then a flat battery may mean that the board can't actually remember the last state and turns on anyway. The battery is a standard CR2032 lithium cell which is fitted in a holder on the board and can be easily replaced.