ATX PSU fan issues

[hackcat]

I have a psu with a large silent 120mm fan (Nexus) that has some built in smart fan control. Under Windows my total system has a cool exhaust, under OS X it can get quite warm. My system is a GA M55SLI-S4 with 4200 x2, bios revision f10 and smart fan control enabled. My case fan is also a 120mm Nexus and it spins at about 1000rpm regardless of OS. My cpu fan can under control go from 1600 to 2500 rpm, but it is efficient and even under stress in OS X it plays no role in keeping my system cool ( I can test this by disabling in BIOS smart fan control and it will spin full speed in OS X). I also know that in OS X my cpu won't run as cool, lack of cool n quiet drivers. However, I'm sure the reason why I get significant heat output under OS X is due too the psu fan not engaging. My quiet system fan alone can't move enough air out of the case but with the psu it does a wonderful job silently. Wondering if anyone knew of a way to force the PSU fan into activity. We aren't talking about anything near critical temperatures, but still a 3 degree increase in hard drive temperature is something I rather avoid.