Well, as you probably know, the m/b is a Gigabyte. Good board.
Does the card have any jumpers on it?
I've been looking at it...everything seems to be thoroughly soldered in place. I had been looking for some little switch or other.
I also tried using all of the expansion slots, each in its turn. All of them have the same effect. Maybe there's a jumper or switch on the m/b?