Can you drop your cpu multi down to x12? If so try..
HTT: x4 or x5 depending on volts
ram Volts: 2.1v or 2.15v
Your cpu should end up at 3Ghz, HTT at 1250Mhz, ram at 1000mhz (500mhz x2).
Cpu voltage should stay the same but bump everything else up. I used this setup to get my ol X2 4200+ to 3Ghz on an old asus M2R32-MVP. I know you have a newer board so it should be fine