Overclocking on the ASUS P5K3 motherboard proved to be interesting. At first we couldn’t get either the Corsair or Kingston DDR3 memory modules to operate at 1600MHz, which shouldn’t be tough to do. After checking the VDIMM voltages it seems that the ASUS motherboard is running more voltage that what is being set in the BIOS. This explained why weird things starting happening when the voltage was increased to over 2.0V. From that point on we kept the voltage to 1.95V for our overclocking experiments. It should also be noted that we couldn’t reach more than 1600MHz when using the orange memory slots (the ones closest to the processor socket). When we moved the memory over to the black memory sockets they easily overclocked over 1700MHz. Basically the take home message here is to keep the voltage UNDER 2.0V and try out both sets of memory slots to see if overclocking is better on one set versus the other.
The Kingston HyperX PC3-11000 memory kit could run 7-7-7-20 timings all the way up to 1500MHz, which was impressive. The HyperX kit didn’t like relaxed timings though and failed to overclock to really high frequencies. The Corsair XMS3 DHX ES memory kit on the other hand really liked running 10-8-8-16 timings and was able to go above 1700MHz with 1.95V!
The Corsair XMS3 CM3X1024-1333C9DHX kit of memory was able to overclock all the way up to 1712MHz, which is an impressive frequency granted it’s at loose timings.
To reach 1712MHz the Intel Core 2 Duo X6800 was run at 7 x 428MHz FSB with the FSB:DRAM ratio being 1:2. The modules were pretty toasty at these settings and were reaching 42-48C on the heat spreaders without a fan on them at idle. After taking notice of how high the temperature was getting we placed the Corsair AIRFLOW over the modules.
Here is a screen shot of the test system running Sandra Xi SP2 with the memory running at 1700MHz. The memory bandwidth was found to be right at 8GB/Sec.