CMOS is a circuitry design/chip while cmos battery (mostly CR2032 on computers) powers the cmos so that it can retain whatever data the cmos holds even when for example a PC (with the BIOS configuration) is turned off.
As to the OP's problem, maybe clearing cmos through a jumper on the motherboard might resolve the checksum error.
To enable it, in the BIOS, go to the Advanced tab - CPU configuration and set ACC to Auto before enabling "Unleashing Mode". We take a look at AMD's latest and cheapest Radeon from the HD 5000 series, the HD5450, see how it stacks up against integrated graphics and find out in what situations it might be a great buy.
This opens up another option underneath that allows the user to specify which cores they want unlocked, providing more than one is hidden. As probably the last Nvidia performance board we'll ever see: this AM3, DDR3 n Force 750 chipset G55 from MSI is one of the few SLI capable motherboards for AMD out there.
- yeah at first when this problem is not around but when this problem occurred I can't able to go to BIOS setup ..