Have you guys found that the 580 gets noisier when a card is in slot 2, due to the lack of airflow and having to run the fans harder?
If there is a full length card in slot 2. That most likely will make a noticeable difference (depends on the RX580 cooler, reference cooler may not be affected that much. Thicker card with open fan may suffer more). Especially when the GPU is under high stress.
But if slot 2 only has a small card (e.g. USB 3.0 card), it shouldn’t make any difference. At least I can’t see any difference in my case (PULSE 580 in slot 1, KT4004 is slot 2).
Anyway, I really tested if there any difference to run the open fan type graphic card in slot 1 and slot 2 (in terms of cooing). Result, slot 1 provide better cooling. Just few degrees difference, but measurable.