Without knowing more, like what others have asked for, my guess is that the mother board in your friends machine will not support that particular card. I have run across a few cases where one particular brand (Asus, Gigabyte, XFX, MSI) card would not boot in some machines but would in others with the same chipset. This may be the case here. This usually doesn't have to apply to "newer cards just that particular manufacture of the card.
Example: 1x Asus r280x wouldn't work but a Gigabyte r280x would. Both tested good in a different motherboard.