PC Running Hot?

[Spydaman]

Every now and then I take the covers off my PC and hoover the dust out. I take the cooling fan off the CPU and hoover the dust out of that too. This time a fan keeps coming on as though it overheating. I've downloaded a monitor and its running at about 70degC (max is 100degC). I stripped it down again and put some heat sink compound between the CPU and heat sink but hasn't made any difference. Any ideas?

[The_Jackal]

If its a stock cooler, try a cheap aftermarket one by say, BeCool. Their bearings are super smooth and reliable and their support is amazing for replacing worn out parts like rubbers for free.
Also check your fans suck in at the front and out at the back/top.
Remember ambient temps will be super high at the moment, so a fan blowing at it will help too.
Also keep the rear unobstructed, the hot air needs to be taken away otherwise it will cook itself.
Dont forget also your gfx card will generate most of the heat too, so clean that fan out too.