Ulinked atm, timings are 5 5 5 15 2T whilst overclocking, 800MHz.
OK. That's cool.
How far should I push the temps? 1.5 vcore, 1.50 vtt and 1.50 fsb?
You can raise the VCore up to 1.5. That should get you to 3.6 GHz. Watch your temps, though. I don't remember what the default MCH and CPU FSB voltages are with the 680i, but you shouldn't need a high increase.