Holy crap, 3 GTX 980 + 1 GTX 970.
Does the 970 always run hotter than the 980?
No, it's because the 980s are watercooled and the 970 is using air cooler (blower style), my case is small...it does not help on air flow, besides the 970 is close to the PSU and the WC pump/reservoir (hot places).
Cheers