Yeah, it really isn't the best way of powering risers. However, I've had no problems with them so far. They don't even feel particularly hot after long bouts of running. I've a tonne of airflow across each rig. it's two rosewill 4u server racks, with 5x120mm high-airflow fans in each. They keep lovely and cool!

I'll keep an eye on things. My theory is, because ethash is more power hungry, if it's stable on this, I'm in the clear.

Thanks again for the help.