Currently I have an AMD FX 6300 6 core overclocked to 4.10 GHz and a gigabyte 660 OC edition. I'm looking to upgrade something, should I go with another 660 in SLI ( I heard its equivalent to a 680) or get the Intel I5-4670K and new motherboard? I use my computer strictly for gaming, recording my gameplay, and uploading it to youtube... and of course just searching the web.
The additional GPU hands down. While the i5 will be better then your FX, you will not notice too significant a difference. With the additional GPU you will. That's what I recommend doing. If you want to upgrade your CPU you could upgrade to the 8350 and not have to get a new MB, but I don't think that would be worth it. Basically I'd get the new GPU. Hope this helps!