Hi

Can anyone give me some advice on what else I can try, to fix a challenge with a computer's BIOS?

Computer was running Win XP and I have now loaded Win 7 Business on to the machine. I set up the BIOS correctly and loaded Win7 Business with no problems. I am also loading this operating system on to 3 other identical spec machines and have only come across this challenge on this one unit.

If the computer is not powered on, but plugged in to the mains with the mains switched on, I can reboot the PC with no problems. However, if I turn the mains off, even for a short period of time, when I then power on the computer again, I get a BIOS/CMOS checksum error. I then either have to press F1 to continue or F2 to enter setup. If I enter the setup, the BIOS (Date, Time, etc) have been reset back to defaults.

I thought it would be the battery on the motherboard. Although I have removed it, checked it on a multi meter and it read the correct voltage. Even though, I decided to replace it with one out of the other computers (which is working fine) and I have also replaced it with a new battery that I purchased and still I get the same error. I have also checked that all internal components, (ram, sata cables, etc) are secure.
The only change that I have done on this one computer is to replace the hard drive from a 250G Seagate Barracuda 7200.10 to a 500G Seagate Barracuda 7200.12, as the 250G drive was failing.
The 250G drive was Sata 1 and the 500G drive is Sata 2, however I have read online these should be backwards compatible, although I may need to put a jumper on to the back of the drive to make it run at Sata 1 speeds (jumper was not supplied with the drive). Could this be causing the BIOS to not remember the settings or does anyone else have any other ideas that I could try? If I need to put a jumper on the back of the drive, would I be able to purchase these from a computer supply shop?

Many thanks in advance

Tech

Since you have switched the possible bad CMOS battery out with a known good one. Also check and make sure the CMOS batter is in correctly, I think most board the battery is + sign up, facing you. And you want to check for any corrosion on the contacts of the CMOS battery socket. Make sure that the Battery is sitting flat and in the socket all the way. I have seen them slightly removed from the CMOS socket and not work correctly. If that doesn't stop the setup of Date,Time, ect at the power on, after the power has been removed. I highly doubt its the Hard drive. On some Mother Boards there is a Bios reset jumper. A good thing to do is Google the model of the Mother board and try to find the jumper for Bios reset.

I am guessing this is happening to one machine, not all four?