More likely that the motherboard is detceting the fan running at such a low rpm during post, it is reporting a cpu fan fail. This happens on my sons pc which uses a 212+ and a GA motherboard. Nothing you can do but disable fan fail detection, I personally would have it buzz for a second than not have the peace of mind of it monitoring the fan.
So the mobo thinks the fan rpm is too low and says the CPU fan is failing, when in reality its that low because its a strong fan that doesn't need high rpms, and thus I should not worry about it. Right?