Grahics card power problem

[ant2k50]

I've got a nvidia graphics card (6600gt) that I've had for a couple of years. However, over the last week or so, I keep getting a power indicator message coming up that says:
"to prevent your hardware from potential damage, the graphics processor has lowered its performance to a level that allows continued safe operation"

The main trouble with this is that the message appears every second which stops me doing anything on the pc without interruption. Does anyone know if I need a new graphics card or could it be my power supply unit? Thanks.

 

[Big B]

What are your specs, including the power supply make and model.

What OS are you using and what driver version do you currently run with the card?

 

[ant2k50]

I've just opened up the pc and cleared out a bit of dust on the heat sink as well as changing the power connector to the graphics card, and I've not had the message come up again....yet. Hopefully I've sorted it out.