Shuttle includes “Dynamic Overclocking (OC) Technology,” as a BIOS feature, which provides overclocking generated CPU clock speed boosts of 3%, 5%, 7%, and 10%. The system also allows manual adjustments to be made to the voltage and frequency settings.
These options allow simple overclocking speed boosts by up to 10% and manual overclocking that provides fairly granular options.
When we first tested the SX48P2’s overclocking capabilities, it was unable to overclock at all. It would only accept multipliers of 6-8 and could not overclock the FSB. Shuttle then offered the X48S10Q BIOS update in October, which we installed over the rather old X48S10F BIOS. The BIOS update resolved the multiplier issue and we were even able to use various multipliers. However, we found that the highest stable overclocking speed we were able to achieve was 4.07 GHz. We were only able to get the system to reach this speed by increasing the CPU voltage to 1.375 V.
Through a bit more testing with a pair of lab processors, we came to the conclusion that Shuttle's Dynamic OC Technology does not work if there is no FSB headroom. The QX9770 would not work with even the lowest setting of 3 % with Dynamic OC Technology, which just seems to only bump up the FSB to achieve its overclocking results.
To confirm that the system remained stable when overclocking, we ran Prime95 for eight hours on all four CPU cores and no errors were reported.