Out of interest, has any of you tried a riserless board with non-blower-style GPUs? Surely they're too close to eachother to work efficiently, i.e. heat cross-contamination must be terrible?...
Almost all of my 3-card FAH rigs were standard fan-type cooling.
That's WHY I first started buying the Gigabyte "ITX" cards - to allow the middle card to stay at least semi-cool.
Card temps WILL be quite a bit higher due to restricted airflow - even Blower cards have that issue as the airflow INTO the blower is restricted by card proximity, they just don't recirc the hot air inside a case nearly as much.
Blower cards on an open air case don't do any better than fan-type cards.
This is precisely what I was thinking of doing after dragonmike brought up the cooling issue - alternating a couple of "mini" cards with the longer dual fan ones. Should be better cooling all around, though my understanding is that the mini cards tend to have cooling issues in the first place.