The stock heatsink should be sufficient for the bios and standard use. An after market heatsink is needed when overclocking, using the cpu at its max for extended periods of time, or in a southern climate.
The only time I have seen temps rise while in the bios is when the cpu heatsink was not properly secured or the clasp broken. Pull the heatsink off, replace the thermal paste, and reattach the heatsink. It may be worthwhile to double check there is not a plastic film from the manufacturer stuck to the top surface of the chipset heatsink. I have had that happen to me before. Drove me nuts trying to figure out the problem.