No, you only need one. You can only have one plugged in. You have the option of buying two in case you lose one or for convenience (for example you can always leave one in your bag to make sure you don't forget it).Do AMD 7970M CrosssFire needs 2 x 300w AC adaptors?
Yes. If your laptop couldn't provide the power to run it, it wouldn't work at all.But does this 300W enough to use this 7970M crossfire for the 100%?
In some forums people saying that this GPU's need a 600w adaptor.