Well the motherboard doesn't ues a 990fx chipset but it should be just fine anyway. Since this CPU already has turbo to 4.1ghz you should be good to go. Start by disabling turbo core completely and increase the multiplier to 4ghz, check for stability and increase voltage if necessary.
In my opinion, an increase of 500mhz is worth it, just watch temperatures and dont go above 63c for to long as it could throttle itself and make your oc useless.
Just keep increasing the multiplier and fsb if you want too, all CPU's vary so there isn't really a "good overclock".
The 970A-G46 is a 970A-G45 (i.e. failure prone VRM design) with a bigger heatsink attached onto it and the "do not overclock" warnings on the MSI website subsequently removed. A bigger heatsink does not make a board with internal VRM design problems and a failure prone record any more safely overclocking-ready. The GA-970A-UD3 has the most overclocking-friendly setup with an efficient quality, heatsinked 8+2 phase. But the one on the 970 Extreme4 although a less efficient but still heatsinked 4+1 phase is pretty good too, and consider of course that the Extreme4 is actually a 990X with 8x-8x CrossfireX and SLI, it's very competitive. http://www.overclock.net/t/1234973/advice-on-gigabyte-g...