I see that the i3 3220 is better than the 2120, so I'll probably get that one. But, the motherboard that you are suggesting me isn't better than the z77 extreme3. If we compare both of them, the z77 extreme3 has a Z77 Chipset, the b75m has a B75 Chipset which is worse.
The z77 has 4 Memory Slots and 32 GB DDR3, the b75m has 2 Memory Slots and 16 GB DDR3.
Why are you saying that the z77 extreme3 is way off my build?