I've tried to force the VSync in Catalyst and it had no different effect, it still gain heat FAST.
Looking around I also tried to use the AFR friendly setting for crossfire as was hinted by some SLI and crossfire users on other forums, but the game still uses only one card. The temperaure only builds up on my main card.
The airflow should be good in my computer and the fans aren't clogged. They've been cleaned recently.
Thank you for your input, I hope to find something that works. Hopefully before my day off is done and gone.