the ones that exhaust out the back of the case usually tend to make the GPU's the hottest.
The best would be a hybrid approach. Identical to the pictured card, but a single fan in the center. Half the air is directed out of the case at the back, half stays inside.
If you want to exhaust more air out of the case from the GPU you could always attach a duct to the end of the card that wraps around and empties out of a spare expansion slot.
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