I just checked my Graphics card and i think i found the problem. The fan isn't spinning properly idle as in it there is resistance and it stutters for half a second and spins quite slowly when under load. I think it is because the Fan isn't recieving enough power and it's cable is a bit loose since i did do some major cleaning just before the problems started. It never used to happen before and it's temperture stayed around 50-60 Idle and 80-90 Under load compared to 75-90 Idle and 110-130+ under load, which reduces all my games Fps to 5-15 FPS when i usually have a solid 30-50 FPS on most games.
More likely the bearing has gone out in the fan, if it is difficult to spin while off that is very likely the case.
It is receiving plenty of power, the amount of electricity required to run that fan is not significant enough to run into many resistance problems from loose connections.
So I highly doubt that it is not getting enough juice, it is possible but not likely.
I would reccomend running around ebay, and picking up a new one for 10-$20
Example:
http://www.ebay.com/itm/Galaxy-NVIDIA-GeForce-GT-430-43GGS8HX3SPZ-1GB-128bit-DDR3-HDCP-video-card-/221196356242?pt=PCC_Video_TV_Cards&hash=item3380548a92Since you would have to spend at least 5-10 dollars + shipping on a new fan anyway might as well go ahead and get a new graphics card for that much.
Temperature sensor broken?
Put your hand near GPU (not on it) and see if it feels hot, if it doesn't feel too hot then temperature sensor is broken and it should be fine
This wouldn't tell you anything, most graphics cards run at ~ 50-60 degrees C, which would feel quite hot to the touch and almost burn your hand, 92C wouldn't feel to much different. Though I suppose the burning sensation would come faster...
Even then, the temperature sensor on GPU's and CPU's are generally built into the processing chip itself, so there can be a significant difference in temperature from what you can feel, and what the core actually is.
Best bet would be to use a IR temperature sensor on the back on the card right behind the GPU, it would read lower than what it actually would be, but it would give you a guesstimate, if it reads 40-50 C and your onboard sensor reads 92C, then probably the onboard temp sensor is wrong.