12 servos on Mega power problems

I have hooked up 12 servos to digital pins on the arduino mega. ive tested them in groups of three and the programming is fine. When I try to use all 12 at once the arduino resets. Should i just power them off a separate power source? I think the power drain through the arduino is too much for it to handle. I also tried plugging in a 12v 5A power supply plus the usb and it still had problems.

Power them off a separate power source. Connect power supply Gnd to a Mega Gnd pin.
Mega can only supply max of 800mA for itself and all devices.

ok thanks. Thats what i figured i just wanted to make sure.