My PSU is about 3-4 years old. I just opened my case up to clean my GFX card and then turned it on and noticed that my PSU fan isn't running. The fan is right at the bottom of the PSU so it's parallel to the ground and the fan is facing the ground. I couldn't really get a good search of the PSU online but it's a cooler master atx12V product no. RP-600 PCAR W/O PFC. It has red numbers saying 600, so I assume it's 600 watts and the fan is 12volts? The issue here is that I've never really paid attention to the PSU fan before and I can't be sure if it's an auto temperature based fan or not. I checked my motherboard settings but there wasn't anything indicative of adjusting PSU fans. Motherboard: biostar Tforce P965 PSU: cooler master atx12V product no. RP-600 PCAR W/O PFC. How big of an issue is it that my PSU fan isn't working?