Hi All, I have a PC which up until a few weeks ago worked fine...although every so often the fan would fire up really loud for a minute or two (PSU fan). This happened last week after using the PC for only 5-10 minutes and the PC switched itself off. Now when I try to power it back up, I get no display on the monitor. The monitor is still working as i've tested with another machine, and i've checked the cables are secure. I notice the hard drive light comes on for the first 10 seconds only after powering up and then nothing. The DVD and CD drives still open and close so are getting power, but the USB ports are not powering any external devices. I've opened up the case and its amazingly dusty...the CPU heatsink is covered with dust just below the cooling fan. All the boards have a layer of dust on them (the machine is around 4 years old). Does this mean the PC has maybe overheated due to the dust and fried the motherboard? Any advice on what I can do to test/correct this would be appreciated. Thanks!