Yep, I have the SmartPower 500 watt. The rear grill air flow is barely detectable, but it is there. The computer has to be quite busy for the air flow to feel even slightly warm. The second fan regulated by temperature has never come on in 8 months. That's because I purposely built my system to be cool and quiet.
In fact my Tripp-Lite 800 watt UPS makes more noise than the computer.
One thing about the UPS fan is that while it has a quiet idle, the fan will start to whirr when power consumed equals 200 watts or more. It took me two months to figure out the whirring was from the UPS fan , and not the PSU fan.
-Bob