My dual slot cooler works perfectly fine. Rarely do my temps get above 53 (usually hovers around 50 while folding). Fan is at 50%.
And for whomever mentioned the PS3 folding, here's what I do: Go to configuration, set f@h to start instead of "life with playstation" when you click the "Life with playstation" button. Then go into the configurations for that, and set it to start after inactivity of 20 minutes (or whatever you prefer). I set mine to turn off after 6 hours, simply because I'm not too comfortable with the heat this thing pushes out (at least it pushes it OUT instead of RRoD lol). That way, whenever I walk into my room, I swipe my finger across the power button and go do something else. It automatically starts folding and automatically shuts down for me =)
And if you have a PSP, you can control the startup/shutdown from the psp anywhere