Wait, are your 3 GPUs crammed next to each other in a MB? Grab a milk crate, some PCIe risers, and a few dozen zip ties, and space those cards out! They NEED their airflow flowing into the fans.
looks like they are in a closed case.
two fans card won't get that hot, my 7970s run even cooler (67C 77C) with 50% fan speed.