System Tweaking and Overclocking

Overclocking

Shuttle includes “Dynamic Over-clocking (OC) Technology”, a BIOS feature that provides overclocking values of 3%, 5%, 7% and 10%. The system also allows adjustments to voltage and frequency settings. These settings allow simple overclocking of up to 10%, and manual overclocking with fairly granular options.

This CPU is an Extreme edition, so we can change the FSB to increase speed, but also lower the clock multiplier to prevent issues like exceeding the speed limit of the RAM. The CPU on this unit would reach over 4 GHz, but it was only stable at 3.8 GHz with a variety of FSB and clock multiplier settings.

To confirm that this was a stable OC, the system was run with OCCT and Prime95 for 8 hours on all four CPUs and no errors were reported. The maximum temperature seen using SpeedFan was 56 ºC. Crysis and Call of Duty 4 were both played or benchmarked for at least 4 hours.

The memory on this system could be clocked to 1066 MHz, but only without any CPU overclocking. Using SiSoft Sandra XII memory, throughput averaged 7.27 GB/s for Int Buff’d iSSE2 (7.28GB/s for Float Buff’d iSSE2) with two or four memory modules.

While we did not change any of the memory settings beyond the defaults, it was surprising that there seemed to be no headroom with this combination of board and memory. For this reason, we had to use the FSB:DRAM clock setting of 2:1 to achieve the highest OC. We spoke to Shuttle about this, and they indicated that the system sent out was an early sample, and newer revisions should perform better. This seems to be supported by the results, as the lower the DRAM clock was kept, the higher the FSB could be pushed.

During this test, lowering the clock multiplier for the DRAM and the CPU allowed the FSB to reach 465 MHz; after that point, the system again became unstable. This is not the highest overclock seen on an X38 or other board, but the benefits of the combination of FSB and clock multiplier really are not seen at rates above this. So while the XPC cannot brag about having the highest FSB or even overclock percentage, we found the SX38P2 to be a very good overclocker.