Safest Core i5 Overclock

Hi guys I have built my comp and it runs fine on stock settings.It is a i5 asus p7p55d ati 5850 setup.I want to overclock the CPU without modifying any voltages.What values should I modify?
Currently I just set BCLK to 150 which gives me 3.0 ghz which is what I want.I have 1600mhz rams and they run at 1200mhz right now.
Any help is greatly appreciated.

Google i5 overclocking guides, they will tell you what each setting does. If you aren't willing to up voltages then the FSB is really the only tool you have. As a quick guide raise it a few mhz at a time to stress test it with prime 95 for 20 minutes. After you think you have found your maximum stable setting then run a stability test of a few hours, I use prime95 (more is better, at 8hours+ you have a fairly solid setup). If it crashes during stability testing then back down on your settings, or start upping voltages.