New Guy Advice

I have been researching this board for some time as I have been building a new GPU system.

I currently have a Chenbro RM41300-FS81 4u case along with 3 AMD 280x cards. I upgraded fans to Delta (the ones people listed in their posts) to help to maximum airflow. I am running Ubuntu Server 12.4 and followed the instructions on Ubuntu Server + AMD Catalyst + oclHashcat HOWTO.

Since my cards are older, I learned that I had to use amdconfig to configure the cards. I first compiled and tried od6config, but when that failed I researched the board until I knew why it failed.

This has been a learning project and I started by trying to use four 280x cards. I quickly learned that the tweaks and airflow could not keep the cards cool enough before hashcat would abort.

I am currently running my cards at 850,1275 with 100% on each fan.

QUESTIONS:

Is there anything I should be doing or configuring the cards differently?

If I used 290x cards instead, are they any better at cooling or would I still be stuck at 3 cards?

My next system will be a larger chasis so it can support more cards. But before I do that, I want to make sure I have this system nailed down.

TIA