RAM Overclocking can be only done on CFW firmware
CPU can be easily and safely overclocked to 960MHz
Please use Neotendo based CFW and replace gmenu2x on SD card.
In the menu select emulator or game you wanna overclocked
Hit SELECT button on that emu/game

Edit ... to change configuration for this item
CPU Clock.
That's all.
CPU can be overclocked with 39K-resistor MOD. Source
