Well as an owner of an FX-8350 gaming rig and loving overclocking, ill let you in on my system and how its been under my tested overclocks and such (Bear in mind, each chip is different)
I am using the Crosshair V-Z board by Asus so we both have the 990fx chipset and we will probably see similar results at least where the board is concerned. Though I am on liquid which will make things a little harder since your on air, but heres how im doing.
I have mine currently 24/7 at 4.7ghz (I have played with higher, but im still working on it for fun)
Temps Range ~28 idle to ~60 Celcius full load (Thats with video cards in my loop also producing heat)
Now I have my voltage currently set at 1.45 to achieve this overclock of 4.7ghz though that maybe a bit high on air cooling. I would stay no higher than 1.425 on the Noctua to keep temps down and no more than a 4.5ghz overclock on all 8 cores because the heat might get a little high. On the Core temp monitors, going above 60 on each core is considered running warm with 70 being hot. I think the thermal monitoring will not let the cores run above 70 (ill have to re-look that up, its not knowlege I keep on me).
Make sure when doing this to just kick turbo off because it can cause issues ive seen. If you want more advice on exact number, I can let you know some more, but for now I hope this help you in your journey!