If you intend to buy a 6 core AMD processor, you might want to wait a while for the Phenom II X4 960T. This processor paired up with ASRock 890GX Extreme3 not only enables the hidden cores, it can also overclock the processor from a default of 3GHz to 4.2GHz on AIR. Of course if you use LN2, you should be able to go higher.

IN our tests, we applied 1.45v to the vcore, the rest are default and we are able to get it to 4.2GHz. Below is a screen shot of it.  Click on the thumbnail to zoom in. Review of the board can be read from here https://en.ocworkbench.com/tech/asrock-890gx-extreme3-amd-890gx-sb850-board-review/