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.