Depending the the mainboard (you never specified) you may or may not be given the option to overclock in the bios. You can always use AMD's Overdrive software to overclock your CPU. I am currently using this software to overclock my 5000BE from 2.6GHz to 3.15GHz. The system is stable and has been for months running under this setting. Overdrive has a nice "AutoClock" option that tests the stability as it adjusts the CPU's settings. Hope this helps.
Link to download AMD Overdrive software
http://game.amd.com/us-en/drivers_overdrive.aspx?p=1
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System Specs:
Motherboard: ASUS M4A78-E
Memory: 8 Gig (4 x 2Gig) G-Skill 1066 DDR2
CPU: AMD Phenom II x 4 955 BE @3.8Ghz
Cooling: AC Freezer 64 cooler
PSU: Corsair 750W
GPU: Gigabyte GV-R489UD-1GD HD 4890
OS: Windows 7 Ultimate 64