About half a year ago i upgraded my PSU and brought a Graphics card for my pc.
Shortly after one of the blue fans at the front of my pc stopped worked. I thought it had just died, so i did not worry too much.
I went to my friends place for a lan and suddenly it started work again I thought that this was cause he lives up a gravel road and my pc got knocked around a little.
When i got home and connected my pc up again the fan stopped working again?
Its easier to imagine a loose connection than it is to suspect your psu can drive a pc with power requirements varying by at *least* 50W, but not run a very low power fan . . . at any time . . . only while at your house.
Try giving the fan a kick-start with your finger . . . while the pc is running . . . at your house. It may not be able to start up from one specific stopped position.