I haven't cleaned my pc in about one and a half years.
That may very well be the reason why your GPU is running so hot. Dust is great at holding in heat because it clogs heatsinks and in the case of blower style cards like the one you have it can clog air pathways
I highly recommend you get a can of compressed air, take your computer outside and blow it out thoroughly including the video card. If you have a dust filter on your case for air intake fans make sure to blow that out too.
This will allow your computer to run a lot cooler in general and might fix your GPU heat issue.
Edit - I recommend reading
this thread for how to clean out your video card with some compressed air
If that doesn't fix it come back and tell...