Patriot Viper memory is sketchy. I had a set of Viper DDR2-1150 ram rated for 2.3V. It would not pass memtest at 2.3V. However, after lowering it to 2.0V, I could get it to pass. But it still wasn't fully stable in my computer, so I ditched it. So, from my experience higher voltage for that ram could make it run worse. If you try it at different voltages and can't get it to run at 1066mhz, then get an RMA.