do i need external power for my graphics card?

[help_me_im_stuck]

i have a new ati radeon hd 7870 graphics card with dual fans. the quick start instructions don't mention anything about plugging it into an external power supply, only to plug it into the PCIe slot, yet it came supplied with two 6 pin cables. I don't have any spare power leads dangling in my case to connect them to. Will the graphics card work from just the PCIe connecter, our do i need a new PSU?

 

[cookybiscuit]

Nope, you're gonna need a new PSU. The PCIe slot is only capable of providing 75w, no where near enough, the card simply wont startup without being plugged in.

Corsair CX430 is pretty cheap and will do the job just fine.

 

[help_me_im_stuck]

Thanks for the quick response cookybiscuit