It just goes to show...

[Pitch]

... What a bit of time spent lapping one's heatsink can result in.

Under load, pre lapping, I was at 76C with the fan speed at 32%.

Post lapping, I can sit comfortable at 57C at lower fan speeds.

[patman01]

Very Nice, any secret you'd like to share on that?

[Pitch]

Lapped with Wet and Dry, polished with Brasso (It took about 20 mins to get it all off) clean with some Rubbing alcohol.

I also applied some AS5 to the Voltage Regulating Mosfets too.

[cadaveca]

I had no luck changing the voltage mosfets TIM, until I sanded the ends of the heatsink a bit

[chrisbard]

This is just unbelievable great ! I have just packed my vcard and it's on it's way to England now ! :P

[patman01]

I'd like to get some better performance out of my gpu cooler, any ideas where I could find some kind of guide or somthing that would explain how to do this? how should I sand the heatsink and apply as5?

[danrok]

There's this in AOA's FAQ section:
Dave's Guide to Lapping

[booman]

I'm to scared to try it. But I have worked on jewelry before and there are some great tools and techniques to get metal shiny smooth. You can use White Dimond and Red Rouge to smooth out all the scratches. You will have to use a Buffing wheel though.
Start with sand paper until you get to a 220 grit or so.
Then you can use a grinding wheel to polish with White Dimond.
Never use the same wheel with White Dimond and Red Rouge.
Last will be the Red Rouge for a shiny mirror finish.

Here is some wheels you can use with your drill or dremel.
Grinding Wheels
Here are some others you can use with a Mini Mandrel
Heatless Grinding Wheels

[danrok]

When lapping, it is very important to place the sand paper sheet on a perfectly flat solid surface. This ensures that the sink stays perfectly flat. You don't want a slight curve on it!

[Staz]

Originally Posted by booman

I'm to scared to try it. But I have worked on jewelry before and there are some great tools and techniques to get metal shiny smooth. You can use White Dimond and Red Rouge to smooth out all the scratches. You will have to use a Buffing wheel though.
Start with sand paper until you get to a 220 grit or so.
Then you can use a grinding wheel to polish with White Dimond.
Never use the same wheel with White Dimond and Red Rouge.
Last will be the Red Rouge for a shiny mirror finish.

Here is some wheels you can use with your drill or dremel.
Grinding Wheels
Here are some others you can use with a Mini Mandrel
Heatless Grinding Wheels

The purpose of lapping is not to get the base of the HSF shiny. It is to get the base as flat as possible. Laying your sandpaper flat on a piece of glass works best for this.