One of two things likely happening,
1. Being mis-reported from the bios. If you haven't double check what it shows for teh vcore in the bios hardware monitoring section (it should show the vcore in addition to the rest of the voltage readings), and compare to what it shows in CPU-Z.
2. The vcore is set to auto in the bios and is running higher than the rated vcore (happens a lot on Asus motherboards).
If you haven't seen it here are the specs for that CPU,
AMD Processors for Desktops: AMD Phenom?, AMD Athlon? FX, AMD Athlon? X2 Dual-Core, AMD Athlon?, and AMD Sempron? Processor
For #1 if what it shows in the bios is at or near 1.325-1.375V, then there is nothing to do but remember the difference when checking with monitoring software.
For #1 and #2 if it is showing the same as in CPU-Z, then you need to go into Advanced section of the bios and under "AMD Overclocking Configuration", manually set the vcore to either 1.35 or 1.375V.