Help with making vaio all in one pc quiet please

Hi Guys.

I have a vaio all in one pc and the noise has become rather loud and the temperature of the CPU was rather high.

I have stripped it down and cleaned all the dust out and replaced the TIM on the all the heatsinks in the pc and now it runs 20 degrees less but still the fans kick in and be rather noisy.

I am looking for some ideas on how to reduce the fan noise.

Is there replacement quiet fans or larger heatsinks to replace fans.

Do these fans work on12v and if so would the trick to reduce them to 7v work?

Any other ideas would be great. The noise is driving me mad.