650 isn't enough for SLI/Xfiring.
I don't want to mention that AMD cpus have terrible issues..if you wanna suggest multicore pros then get a standard one..like i7.
Here's your score-
http://cpuboss.com/cpus/Intel-Core-i5-3570K-vs-AMD-FX-8350
Yeah, AMD is that pathetic that it can't even cope up with a i5 even..leave out i7.
Most of the amateurs get overwhelmed when they see that "8 core processor" but actually in reality it performs poorly in gaming.
The amd build you suggested is mainly for videoediting rendering(70%) and less gaming.(30 %)