I'm running a sempron 3100+ 754 chip and I've got an unlocked athlon 3700+ and it just will not work. I've got a Bali motherboard (GA-K8VM800MNF) and updated the BIOS. Can this change over work.

What exactly does not work ?
It doesn't start at all ?

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World's best Red Alert 2: Yuri's Revenge mod and Star Trek: Starfleet Command 3 mod: Overmind.ro

doesn't start at all, the fan runs at normal speed and the power button flickers

Try to reset the BIOS.
Make sure the 4-pin black/yellow extra power connector is connected.
If it still won't strart, try removing the video card, RAM and IDE drives and repeat the BIOS reset. Check if you hear any beeps at this time.

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World's best Red Alert 2: Yuri's Revenge mod and Star Trek: Starfleet Command 3 mod: Overmind.ro

Maybe your overclock is causing the problem. Resetting the BIOS will reset your CPU, RAM, and other things to stock speeds/timings.

There are a lot of good AMD overclocking guides; I suggest you follow the advice in those and you should get a stable OC.