It has been fun having a second shot with these CPUs, but it's nice to finally put the comparison to rest. What did we learn?
Which Dual-Core CPU is the Better Gamer?
Let's consider gaming performance. The first thing we learned is that a stock Pentium G6950 is not a good option for a gaming rig. It suffered a notable performance penalty compared to the Phenom II X2 555. So, entry-level games not intending to overclock, AMD's Phenom II CPU would be the best bet.
However, if you plan to overclock, the story changes significantly. Our Pentium G6950 easily made it to 4.3 GHz and kept pace with the overclocked Phenom II X2 555 without a problem. At this point, either CPU is a viable option for gaming, and your choice may depend on your preferred platform more than anything else.
There is the possibility that you might have some luck in unlocking dormant Phenom II X2 555 CPU cores. We did. But even with all four cores operational, there is very little difference in raw gaming capability, and unlocking dormant cores is not a guaranteed success. More than two CPU cores make the most difference to gamers in scenarios where applications are allowed to run in the background, but if this is how you game, you're probably better off with a similarly-priced Athlon II X3 instead of taking a chance on a Phenom II X2 555.
Which Dual-Core CPU is Better in a Productivity Machine?
When it comes to general-purpose desktop usage, the stock Pentium G6950 and Phenom II X2 555 trade blows and end up with similar average performance, which is surprising considering the Pentium's smaller cache and 400 MHz clock speed deficit.
However, once the Pentium G6950 is overclocked, it easily bests the overclocked Phenom II X2 555 by a wide margin, and makes a strong case in applications that don't take advantage of more than two threads. Remember, the Pentium G6950 starts off with a 400 MHz lower stock clock rate compared to the Phenom II X2 555. But when you factor in an overclockable 32 nm manufacturing process, there is a lot of room to grow.
The Phenom II X2 555 shines on the desktop when its dormant execution cores can be brought to life. Once again, the user has to decide if it is worth taking a chance on buying a Phenom II X2 555 that might not have working dormant cores or spend similar money on a quad-core Athlon II X4 with four cores guaranteed to work. We generally recommend going with the processor you really want, rather than risk unlocking, since AMD's product stack is so tightly packed.
At the end of the day, both of these CPUs offer solid value. The Pentium G6950 is a decent starter CPU with tremendous overclocking potential and a platform that has a lot of room to grow with the user. The downside? Poor gaming performance at its stock speed.
Of course, let's not forget the Phenom II X2 555, a processor with better gaming and application performance at its default clock rate that can be easily overclocked through multiplier-based overclocking. More advanced users can even try their luck and see if this CPU has usable dormant CPU cores, transforming this processor into the equivalent of a quad-core Phenom II X4 955. The downside? There is not as much overclocking headroom compared to what the Pentium G6950 offers, and there's a good chance that the disabled CPU cores simply won't work.
As a side note, we're really impressed with both the Gigabyte H55M-UD2H and Asus M4A785TD-V EVO motherboards, as both provide a simple overclocking experience at a $100 price point. And for $20, we couldn't be happier with the Cooler Master Hyper TX3, a great cooling upgrade for performance enthusiasts looking to get the most out of a strict budget.
In the end, what's the best dual-core CPU for the budget builder? That depends on what you want to use it for and only you can answer that question. Hopefully we've given you enough information to make an informed choice. But let's not get tunnel vision here. There are some other ~$100 CPUs worth considering, too. The Athlon II X3 or X4, for example, might be a better option for folks with specific needs. Isn't choice a great thing?