Would I really see a difference upgrading from A10 5800k to an Intel i5 4430? It's not exactly a cheap upgrade and due to the fact I'm a student. In the future I'm also planning to add another GTX 660 in sli, not sure if that would influence the decision.
You should see an improvement. However, I recommend you actually spend a little more money so that you can buy an i5-4670k and a Z87 motherboard. That will allow you to overclock for even better performance.
The i5-4670k (3.4GHz) is currently selling for $225 at TigerDirect vs. $240 at Newegg. The cost of an i5-4430 (3.0GHz) is $190 at both stores. That's just $35 more. The cost of a Z87 chipset motherboard generally starts a about $110 which is not that much more than a lower end chipset that does not allow for overclocking; about $20.
For maybe $50 - $60 more than the i5-4430 you can get the i5-4670k and a Z87 motherboard. At default speed you will get a 400MHz increase (3.4GHz vs 3.0GHz). According to a survey done by Asus, 70% of the i5-4670k CPUs are capable of being overclocked to 4.5GHz. So spending just a bit more outside your budget you will likely to get a CPU that is clocked 50% higher than an i5-4430 which means a 50% increase in raw performance. The does not mean you will get 50% higher frame rates in games though.