Problem with a card - hash rate drops and way low fan speeds?

I just build two machines for mining altcoins. Each card is using 6x Gigabyte R9 270s that I undervolted and for the most part they all get 480-490 kh/s and run around 70C. However, one card keeps dropping down to under 100 kh/s for no apparent reason. It is not overheating, but rebooting the marching brings it back in line.

I did notice the fan speed on it is consistently lower than the other cards even though temperatures are reading the same? I am kind of at a loss here. I lowered the clock and memory speeds on it slightly and it seems to be more stable at (430 kh/s), but the fan speed is still way way low (~15%), so this concerns me a bit. Obviously something is a little off about this card ? Should I RMA it? Will they test the card?