I have been TRYING to Clear the CMOS as at POST,I get a single Beep then another single Beep and the POST starts again cyclically,so I am unable to run any operating system or  start up a cdrom boot disc..NB I have removed the CMOS Battery and only have the minimum of components installed and LEFT the PC in this state overnight but cant RESOLVE the problem.Anyone have any ideas??? MichaelYou have not stated the motherboard model number. If you find that out you can Google the motherboard specification and find out the BIOS manufacturer, (for example AMI). Then you can find a list of beep codes for that BIOS maker.  Most MSI boards use an AMI BIOS, and for these, two beeps means there is a RAM ERROR, to be precise a parity error in the first 64K. This could be due to a badly seated or faulty RAM module. First try reseating the RAM, then if that does not clear the fault, if you have more than one you could try each one in the first slot to see if one is faulty. Otherwise it could be the motherboard component failure.