Apart from all that, the computer is not a branded one, so if it's not assembled from parts, it might not have the necessary options in the bios.
Check the bios, and if you start overclocking, remember to monitor the temperatures, especially in stability tests of course. The maximum temperature for that micro, check it on the intel page.Regards.
the pc is not a branded one, about the temperature I'm not sure if that's the one that's marked on the page in Tcase 61.4°C
Intel
Core™2 Duo Processor E6300 (2M Cache, 1.86 GHz, 1066 MHz FSB)