The Phenom II X4 965 BE is utilizing Cool & Quiet
http://www.amd.com/us/products/technologies/cool-n-quiet/Pages/cool-n-quiet.aspx
This is used just to conserve energy.
When your using your PC like in a game it runs at normal speeds.
It can be shut off usually in BIOS if you desire.
Check the maximum CPU TDP of your motherboard and the list of supported CPU's.
You can go to Biostar's website also to confirm it under support.
http://www.biostar.com.tw/app/en/mb/index.php
If you are above the maximum TDP there is a good chance you could burn out your motherboard.The TDP of the Phenom II X4 965 BE is 125 watts.Many of the cheaper Biostar boards only support CPU's of 95 watts TDP.
If your looking for a good gaming CPU of only 95 watts TDP I would recommend a Phenom II X3 740 BE (better) or an Athlon II X3 450.
If your stuck with a Phenom II X4 965 BE you could save it for a new build with a better board.By the way many of the newer Athlon II X2 CPU's will outperform the older Athlon X2 6000+ in gaming plus they have a much lower TDP.The Phenom II X4 965 BE would easily outperform an old Athlon X2 6000+
See here
http://www.anandtech.com/bench/Product/102?vs=28
It's not Biostar's fault if you chose the wrong motherboard.