As per the Radeon HD 4850 board we looked at recently from Sapphire, this particular Radeon HD 4870 offering uses AMD's reference clock speeds, meaning that it sticks with the 750MHz core and 900MHz (3.6GHz effective) memory clocks we just mentioned.
While the Radeon HD 4850 requires only a single six-pin PCI Express power connector, the more demanding specification of the Radeon HD 4870 necessitates the use of two six-pin power connectors, which can be seen here on the rear of the board.