I've ran my OCZ platinums at 230Mhz without touching voltages.
Take into account that the maximum overclock not only depends on the CPU but on the board as well. I have a QX6800 that I can't get past 3.2Ghz on a 4 phase board but I tested it on a 6 phase board with modern VRMs and got to 4Ghz with ease.
Before plunging for some RAM try setting RAM at a lower ratio and find out just how far can the CPU go on your particular board.
My other rigs:
OCTANUX - Conroe865PE - QX6800 - 4GB OCZ Platinum EL - HIS HD4670 AGP - SB Audigy 2 ZS - BFG PPU
phenomenal - AM2NF3-VSTA - 965BE - 8GB OCZ Platinum LV - HIS HD3850 AGP - SB X-Fi - Asus PPU - *WIP*
Green Tea - 939A8X-M - FX60 - 4GB OCZ Platinum EL - 7950GT AGP
Re-build - CT-6VTA2 - PIII 600E - 384MB PC133 - Voodoo 5500 AGP - SB16 ISA
BLUELINE - H61M-GE - PDC G645 - 8GB DDR3-1333 - Powercolor HD7750 - 2xTV Wonder 650