If all you're doing is raising the FSB and keeping the RAM low enough, I'm almost certain that you still need to raise the Vcore some more to get 2.5 stable. What is the vcore set to when you try to boot beyond 2.5? I know you said a notch or two, but what does that work out to be--I'm guessing around 1.37v? That's probably not enough. Keep in mind, you have a high VID--1.325v (I do too)--so on average, your 2180 will require more voltage than one with a lower VID to overclock to the same extent. I'm telling you--you'll likely need around 1.45v in the BIOS to get near/to 3.0GHz. I have the same VID and virtually the same motherboard. Also, keep in mind, voltage requirements increases almost exponentially with clock speed--so you might need to start increasing the voltage quite a bit more just to go up, say, 100MHz.
What actually worked the best for me was leaving the voltages on "Auto" (raised my vcore properly, and put my RAM at 2.0v, just FYI--all other voltages were not changed) and making sure the RAM was close to 800MHz. If you go beyond 800MHz with your RAM, just put the timings to 5-5-5-15 to be on the safe side while getting your CPU to 3GHz, and then go back and work on them later.