[pereb27]

I'll make my own thread about this later, but posting here for now.
So... the PS3 heatspreaders are actually made of copper covered by a thin layer of ( according to @KillerBug ) zinc. I guess this is true because it doesn't exactly look like aluminium to me. Anyway Zinc has a bad thermal conductivity (116W/mK as opposed to 237 for aluminium and 401 for copper). Not only lapping the heatspreader will make it so it makes better surface with the heatsink, but it will also remove that thin layer of zinc! (it's about 0,1mm thick).
So far I've lapped the heatsink side, I'm considering lapping the die side, but this is very tricky so I have to work out how to do it.
Anyway as KillerBug said, the heatspreaders look flat while they really aren't!
Here are some pics :

- Original



I started lapping the RSX with 400 grit, then I noticed this :


As you can see, the zinc came off very quickly on the edges but is still there on the center, indicating that the surface is not flat. I switched to lower grit right away.
I used 180 and 280 grit paper depending on how much zinc was left, the less zinc the higher grit (I had no lower grit back then or I would have used it). Once all the zinc was gone, it looked like this :


I lap for about 10 minutes at each grit, the whole time. Works pretty well.
I then switched to 600 grit, resulting in :


Looking pretty smooth so far. I then used 800, 1200 (for some reason it looked rougher on 1200 than 800 <.<), 1500 and finally 2000 (I lapped for about 20 mins at 2000, since it's the last stage where you're basically "polishing" by using a very high grit paper... btw I seem to get better results if I do NOT lubricate the IHS with dish soap during this stage, just water on the sandpaper seems to work best) :


I have successfully converted my PS3 RSX IHS to a mirror. :D
In all seriousness, the mirror-like reflect indicates that it is nicely polished, and almost flat (although the IHS itself is actually scratched, see below).

Here are some pics of the Cell.
This time I used 60, 120, 180 and 280 grit paper until the zinc cover was gone (god that was much faster) :


Then proceeded to lap it with 400, 800, 1200, 1500 and 2000 grit.

400 :


800 :


1200 :

Once again don't ask me why it's rougher... All the grits are from 3M except the 2000 so I don't think it's a matter of different quality paper.

1500 :


And finally 2000 :


Once again there is this mirror finish proving the IHS was nicely lapped. However the IHS's still look very scratched, however I believe this is normal as we're using sandpaper, and it's not worrying matter (correct me if I'm wrong). Best way to know how good you've lapped your heatsink is to check the reflection like I did in my pics, and don't mind the scratches.
Here are both finished IHS's :


Now I need to do the heatsink, and possibly the underside of the IHS. Any tips welcome x)

[Aifah0qua]

yeah, i know, but throwing it in the oven and baking the motherboard should be done only in the worst case scenario of not being able to get a heat gun anywhere, because heating all the components to 180 °C puts a lot of strain on the motherboard, and may damage it... if you really want to go that way change the compound also under the northbridge heatsink, or the cooked compound won't work as well as before : )

[KillerBug]

Originally Posted by pereb27 Now I need to do the heatsink, and possibly the underside of the IHS. Any tips welcome x)

Those look beautiful, nice work! I think you might now see why I recommend using a dremel to remove the ridge from the bottom of the CELL heat spreader. I think the PDF might need a second revision now...

[pereb27]

I think I'm actually gonna relap the RSX a bit from 400 or 800 grit, because its surface looks more blurry than the Cell's <.<

[KillerBug]

I think you are going too far; they are already plenty flat...and the fact that you have copper surfaces now means you have far better conductivity than they did from the factory.

[pereb27]

Originally Posted by KillerBug I think you are going too far; they are already plenty flat...and the fact that you have copper surfaces now means you have far better conductivity than they did from the factory.

I guess they're good this way but a bit better won't harm :P the RSX seems to have deeper scratches than the Cell, I think I didn't spend enough time at 800-1500 grit before switching.

EDIT : Nvm, can't seem to get better results... I did a bit of lapping at 800, 1500 and 2000 and the RSX still looks the same. I guess I'll just leave it at that.
Anyway, still have a lot to do I guess. Time to get to work!

[pereb27]

Here are some pics of heatsink lapping.
The end result wasn't as mirror-like as the heatspreaders... I guess this is because it's made of aluminium as opposed to copper.



As you can see, this one needed lapping badly. It seems most heatsinks from the BC models are like this to an extent. Doesn't help...

After lapping :




Doesn't look as good as the copper heatspreaders but it should be just as flat
I sanded the part with the screw holes a little,to make up for the metal lost during the lapping of the heatsink.
Tomorrow, the hardest part (or maybe just the one that takes the most time?) : lapping the die-side of the heatspreaders x)

[Melva8623]

Thanks Greg.

I think this needs to be a sticky as well.

[KillerBug]

Looking good...that thing is going to run so cool once you set the fan speed...

[pereb27]

More pics :D
Today I only lapped the underside of the Cell IHS. I didn't have access to a dremel so I... sanded the ridge off >.< A bit more and I would have gotten RSI xD

Warped heatspreader is warped. <.<



Took me a good 3-4 hours to sand that stupid ridge off >.< Then started lapping when it was about 99% flat (got a small comma-like zinc mark so that I can tell which side is which :D) :

400 grit


800 grit (I'm starting to think whether the reflection is good or bad depends on the direction I lap the heatspreader)


1200 grit


1500 grit


2000 grit



Tomorrow I'll do the RSX die side. And hopefully I receive my thermal paste, I wanted to use my PS3 this weekend :< Those guys are taking longer than expected.