Why am i having problems booting with my overclock?

i have a dual core e7200 processor and the thing has only boot at 3.8 ghz once now, but during that boot it was flawless as i tested it using super pi and i gamed in BC2 for 2 hours. I also tested my WEI with it. in order to get that clock speed i did a 9.5x multiplier with an fsb of 400 mhz (ddr2 800 ram running in 2:1 ratio). however i just moved my computer to a different room and now even if i change my voltage from the 1.32 that i used to attain 3.8 ghz up to 1.45 volts, the computer still refuses to boot at anything more than 8.5x multiplier with fsb 400 (3.4 ghz). why am i having these discrepancies in boot-ability if my temps never went over 55C under full load at 3.8 ghz? does it need even more voltage? am i grounding it out? does my motherboard suck? maybe i could use a bios update? my motherboard is a microatx gigabyte g31m-s2l