I've had my 9500 GT graphics card for probably about 1-2 years now, and just recently it started reaching temperature of around 70-80 degrees Celsius idle. I am fairly sure this isn't normal as it never did this before but then when I try playing any game, even at its lowest setting my 9500 GT will start shooting up to around 110-116 degrees Celsius. Could somebody explain what is going on and maybe offer some advice on how to fix this? Thanks.
As Mubin says, try removing the video card and using a can of compressed air to blow out the accumulated dust/debris. Compressed air is $7 at staples, home depot or you can mail order from newegg. Trying to do this with a dust-buster is a bad idea.
If cleaning the heatsink/fan doesn't fix the high temps (and the fan is turning!) then the heatsink is loose. Remove it, clear the old paste/pad off (use swab + alcohol, video on youtube if you want to watch) then apply artic silver or equivalent. $5 http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Above 100C you are damaging your card. It will fails in week/months. The high temp ups leakage current which increases the temp. You need to stop using the card until it is fixed. 110-116 degrees Celsius" --> really bad.