GIGABYTE GA-G41MT-S2PT & Xeon E5450

I seem to have the same problem with my mainboard GA-G41MT-S2PT and the Xeon e5450 processor.
I tried flashing several BIOS-es found with Xeon E5450 microcode - nothing worked.
HWinfo says the microcode update revision is A0B.
Some time ago I set the processor to 75% minimum from its 3.0 GHz frequency.
But I don't play games or compress videos - I need a processor capable of changing it's speed.

Any fixes..?