The problem in this case is that the Intel(R) Core(TM) i5-760 processor was designed to work with DDR3-1066/1033Mhz RAM. Using faster RAM will certainly cause problems. For more information, please refer to the following website:
If you manually changed the Host Clock Frequency of the motherboard, in order for the RAM to work at DDR3-1600Mhz, the processor clock speed will be affected as well, which would explain the overclocking.
Thanks for the quick reply.
What CPU or upgrades would you recommend in order to get the full speed out of the RAM and thus full system speed?