You're going the wrong way... oc'ing is up, with no limit! Seriously, 3.0G with such low voltage is great - shows a lot of potential for the chip. Once you're comfortable with your oc, save your BIOS settings and start upping that FSB.
I use OCCT (
Download - OCCT Website english) to test my rigs; usually a 30 min. custom test shows stability. Then I raise the FSB again, with Vcore if needed.
To give you a rough idea, I managed 4.1Ghz with one of my Q6600s (Vcore was 1.6V), and that same Quad was stable for folding at 3.8GHz (Vcore 1.525V) - all under water, mind you. sswilson did the same, but with less Vcore.
With the Q6600, you're fine as long as it doesn't pass 60C under load and you don't give it more than 1.5V Vcore. I believe you'll reach the thermal limit before the voltage limit if you're using air.
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