|What's to understand? The way the chart works is plainly explained. The cards are broken up into groups that have similar performance & those groups are listed with the most powerful cards are at the top. The performance level drops as you move down the list. The GTX 660 is on the 6th level (or tier), so it's a very good card.|
As for the link you posted, the hardware list is OK except for the RAM. The FX-6300 supports DDR3-1866 so DDR3-1333 is going to cause a bottleneck. And since there's only one stick, it will force the system to run in single channel mode causing an even bigger bottleneck. I suggest you change to a matched pair of DDR3-1866, either 2 x 4GB or 2 x 8GB.