The same configuration is solid for me too! I was able to drop the voltage even further while passing the integrated testing multiple time in a row with full 16000 iterations, but I got reboot soon after playing with Maps. I have noticed this with other combinations too, that the integrated test tool is apparently not pushing the system to its absolute limits, because Maps usage can easily reboot a passed overclocked configuration. Yeah, why not using that if it works! I have tried 1400 MHz as well and I can't get it stable even with high voltages. However, I got 1375 MHz stable with fairly reasonable 1.325V. Have you tried that?