I just bought a new Enermax 350 Watt power supply, model EG365P-VE(FC). It's hooked up to an older Abit BH6 (Intel BX chipset). Now this PS has two fans, one on the bottom and one in the back like normal. THe bottom one is working fine, but the normal back one is not spinning at all. Why could this be? The PS has connectors to hook to a motherboard with PS fan monitoring support but mine doesn't have that and it never said anywhere that that had to be a requirement. Is the rear fan maybe heat sensitive or something and the fan turns on at different times?
