well, I know you didn't want to hear it, but you're not going to get any better single thread performance upgrading to a 6 or 8 core cpu, your motherboard is also widely known for overheating/throttling when trying to overclock, so don't try that either. What's your current gpu and what games are you trying to play? A used locked i5 sandy bridge on ebay is often times the same price or cheaper than a fx6300 or 8320/8350, yet nobody ever talks about them, if you don't care about usb 3.0, h61 motherboards are also cheap on there, although a b85 shouldn't cost much either.
Many people "upgraded" to the 6300 from the phenom 965 and they said it wasn't that big of an improvement at all, so I'd say just save up for intel, it would be the...