3570k @ 3.4ghz and above for a short time.
The PSU isn't bad, it's just from an old build so if i can stick with it rather than replace it just for one connector then i would rather do so. From what i can see there hasn't been any down clocking, it even allowed for a bit of overclocking headroom on the 4pin but i didn't want to push it without an 8pin connector.
I'm happy to go out and get a new PSU but if there's really no need to other than for the connector to be native to the PSU then i could use the money for a better cooler.