I have not used a cooler with the CX7. I have it elevated in the back, but no cooler. I had bought a few with my GX7 and they were good. But after the EX7 and seeing that it was better just to elevate rather than use the coolers (which fans are not always in the right position), I just stuck with that for the CX7.
When I am gaming - the most strenuous time - I have the fans cranked to max.