Thanks for the answers Edwin, I was half asleep when posting and realized that possibly I might have mislead you on the big chip because it has an aluminum fin on it.
Can this fin be removed without harming the chip to confirm that it is a KT600 chip set?
Also this a refurbished mobo. Would it have been done with a lesser chip set and bios?
Do not remove the heatsink please as you might get problems to attach it back.
It is possible your refurbished board got a chip originally belonging to a diferent motherboard but that doesn't mean it still has an old Bios inside. They should have flashed a proper bios and then install it in your board.
KT-600 and KT-400A should be fully compatible as the -400A is usually a downlabeled KT-600 either per customer demand or because it was not fully capable to reach the -600 specs.