Recently I upgraded the CPU in my machine from a Celeron 667 MHz to a Celeron 1 GHz. However, when the computer performs the power-on self test the computer seems to think the old 667 MHz chip is still in the machine, and returns the message: ‘CPU changed or inoperable’. The message refers me to the BIOS setup to select the type of processor. However, I cannot change the name of the processor, but only modify settings for the old CPU. In other words, there is nowhere I can select the 1 GHz processor.

It seems the BIOS has triggered the ‘Speed Error Hold’ safeguard on your system. This will prevent the system from booting when the clock speed of the CPU is different to the speed coded on the CPU. This is designed to protect unwitting users from accidentally overclocking their CPUs (running the CPU faster than the advertised speed). The BIOS may not be aware you have installed a new CPU, and thus thinks the CPU is running at the incorrect speed. You could always disable the Speed Error Hold function in the BIOS, which should solve the problem. However, this will probably have bad side-effects especially if your BIOS thinks your old 667 MHz CPU is still installed. The BIOS should automatically detect the current CPU installed in your machine. You generally cannot manually specify the type of CPU in your machine. Try entering the BIOS setup before the error message appears, by pressing the relevant BIOS hotkey (e.g. DEL). Once in the BIOS setup, have a look around for the CPU settings. On newer motherboards, this may be contained in the ‘CPU Soft Menu’. According to my theory, the motherboard should detect the new CPU. (if not, please contact me again with specific information regarding the motherboard brand and model). If you need to specify the CPU operating speed set this to the advertised speed of your CPU.

If you don’t see any setting in your BIOS for the CPU, then things become marginally more difficult. Older motherboards used jumpers to specify the CPU settings, whereas newer motherboards employ a more user friendly approach through BIOS menus. If your motherboard uses the jumper settings, there isn’t much I can advise you on through correspondence. You may need to take the computer to a technician to be fixed.