Higher voltage doesn't always mean faster speeds or better timings for ram. Each stick is different. I had Patriot Viper ram that was rated at ddr2-1150, 5-5-5-15 @2.3V. But it would Always fail memtest86+. After much troubleshooting, I found that the ram passed memtest86+ 1150mhz, 5-5-5-15 @2.0V. So, for some ram too high of voltage will cause worse performance.