Heatsink mod, how do I separate these two pieces?

So I want to replace some aluminium with copper on my GX620 heatsink.
The aluminium part seems to be attached to the copper pipe with some sort of epoxy, I guess

How do I remove it?

And should I use epoxy to affix the new copper sheet to the copper pipe, or is there another way to do it?

Copper sheet I will use:
New Copper Sheet 100mm x 100mm x 0.9mm C101 - eBay, Metalworking Supplies, Metalworking Milling Welding, Business, Office Industrial. (end time 20-May-10 15:08:45 AEST)

I've attached a pic to show which part I want to remove, then replace with a copper sheet:

 

Well, since the heat pipe is copper it is very fragile and therefore i would never try to pull it off unless you are extremely sure that the "epoxy" you may assume it is, has no bond between the copper. Pure acetone would do the trick in removing epoxy, since most epoxy's are petroleum based, i have no idea however, if it would react with the copper causing any un-needed pitting or cosmetic blemishes/stains.

Attaching it:

-solder? the heatsink just sits there, there is little physical stress on the copper, apart from thermal cycling

 

It's likely soldered because that provides a thermal connection, and an epoxy would be more likely to be insulative.

I don't think you're going to be able to do what you want to do, and if you try you'll likely destroy your heatsink.

 

If it's soldered, you can pretty much bake it apart and bake it together.

Make sure you've got nothing that'll melt attached to the heatsink and find a way to put a little bit of force between the metal plate and the heatpipe. You can elevate the plate and let the pipe "hang" from it, etc.

Anyway, 10 minutes at 400F should melt the solder (hell, 10 minutes at 385F did it for me; I'm just saying 400F to be "safe"), and the heatpipe will just fall away from the plate.

Putting it back together, just clamp your new plate to the heatpipe (hopefully there's still solder residue left) with something that won't burn/melt at 400F, and bake for another ten minutes.

Anyway, no guarantees here; this worked for me and I did it by accident.

 

I am planning to do exactly the same trick for my MS-1722. I just bought a different graphics card for it, and the old heatsink won't fit. I have to modify it then. I will use Arctic Silver Thermal Adhesive to attach my copper sheet to the heatpipe. Any more comments on how to separate the existing aluminium sheet from the copper heatpipe are most welcome.

Commander Wolf, I will give Your method a try and see if it works. I will keep You all posted.

 

I do have a spare GT627 heatsink, so if this mod goes bad I will just mod that one and use it.

Thanks for the help

 

If its attached with adhesive put it in the freeze.

 

If you replace it with copper, where will the screws go ?
do you have the holes in the new copper?

I'd put the copper shims ontop of the copper bar instead of replacing the aluminium

 

I will drill the holes.

I believe this mod will be a lot better than putting copper onto the bar.

My old 9800m GS ran much cooler than both my 9600m GT and 9500m GS (idle temp 5C cooler, max temp ~8C cooler).
The reason is probably because with the 9800m GS I used a GT627 heatsink (copper), but with the 9600m GT I use this aluminium heatsink (from the 1651 ID1).

 

Use a torch to exclusively heat up the areas where the plate is secured with solder would work fine.

 

cmiiw, but the aluminium part is only holding area for the screws right?
the surface that touches the chip die should be the copper bar part,
so adding copper shims to copperbar should help lower the temps

 

With this heatsink, the surface that touches the GPU die is aluminium.

Though the surface that touches the CPU die is copper, that's why I'm leaving the aluminium on the CPU.

Anyway, I'm going to try using a heatgun first, if that doesn't work I'll use a torch.

I found some 40mmx40mmx0.9mm silver sheets. But the price is a bit too high to use as a heatsink. Though I do wonder what temps I would get with silver vs copper?

 

Thermal conductivity of Aluminum: 136 BTU/hrxFs
Thermal conductivity of Copper: 231 BTU/hrxFs
Thermal conductivity of Silver: 247 BTU/hrxFs

Only a marginal difference (between silver and copper I mean).

Link for thermal conductivity of various metals: http://www.engineersedge.com/properties_of_metals.htm

 

I think it's best to leave that aluminum plate the way it is. Copper is softer than aluminum, meaning when you tighten down the plate it may slightly go out of shape if it's made out of copper. Keep the aluminum plate I doubt that you'll see any change in temps.

 

This worked, except I used a heatgun on 300C.

It fell right off like you said. Getting it back together was a bit harder and I accidentally bent the heatpipe several times.

Right now my mod has failed and I made a big mess.
Temps are higher than before and don't stop climbing steeply even when I hit 80C.

I'm going to try to salvage this, if not then I will go all out and stick a tiny pump in there to water cool this thing, will upload a photo of the mess soon.

 

If im not completely mistaken 300 F should be around 200 C.
That could explain why your heatpipe was easily bendable.

Wish you good luck and hopefully you get the cooling solution working again.

 

The heatpipes will bend even if they're cold, if you're trying to manipulate them with too much force. If you bent the heatpipe, it may have narrowed the channels that the liquid needs to flow through and reduced the efficiency. The pipes may be unrecoverable.

If you can get your hands on another heatsink, you could try using a separate, smaller, lighter copper block to solder onto the heatpipe. It's easier to manipulate a smaller block than a giant one. Lock it down to the motherboard with a stiff bracket instead of drilling through to simplify it.