Is my video card dying?

Today when I was using my PC I saw particles on my screen and a fuzz around on my desktop. In the past I have Overclocked the video card ALOT. I checked to see the GPU one time and there was black soot around the GPU. Temperatures are around 138-150 idle and In Games the temp goes high. Overclocking in the past caused many Blue screens and even The Vista Rating was only 3.5. It is an 8400gs. Should I get a new one. Im thinking of a ATI 4670. Or anything of the same size. Not a 9600gt. I have a small case and only standard size video cards can fit. Please help.|||Yeah get a new one and overclock the bejeesus out of it to....|||Yes, you fried your video card from improperly overclocking it.