Hi, I checked it, only 1 fan is spinning, I'll turn that option on. Yesterday dell support told me that low (or not) spinning fan is a energy saving feature, looks like it is.  I should read the RTFM. XD
Hi, I just bought a R720xd w/ 1 E5-2620, 16GB DDR3 x4, 3.5" 4TB NL-SAS x12 and 2.5" 146GB SAS x2, I find the temperature of PSUs are about 50°C(122°F), the fans in PSUs do not rotate(I know that they are good, because they rotate at startup), and the two 2.5" HDD above these PSUs report their current temperature are  54°C. I've called DELL support, they told me that is normal, don't worry, but I don't like HDDs work at high temperature, here is my question: 1. anyone else find this problem? 2. is there any way I can force the PSU fan rotate? 
Temperature of R720xd Power Supply Units are high!