My current setup:
stable at 205GH/s w/ 6 v1 H boards (1 August & 5 October). Pencil mod on the August board, no changes to October boards. I've removed all heat sinking and other physical modifications from the August board.
It took quite a bit of shuffling to find a board order which worked well.
The cardboard prevents board flutter/vibration in the high speed airflow; this cut down on SPI errors noticeably. It also directs more of the airflow toward the power supply section of the boards.
I bought a few of these guys:
http://www.supermicro.com/products/chassis/4U/748/SC748TQ-R1200.cfmlightly used from a local recycling place for $30/each, 1200W power supplies included, so the whole thing is now
rack mountable in 4U, little single included. With the case on it's quite clean.
The rPi controls the little single w/ cgminer; stratum proxy for chainminer runs on a remote host because it's much easier on the rPi that way.
