[SOLVED] Corrosion on cooler base?

jhsachs

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I'm assembling a system with an LGA1155 CPU. Just before applying the thermal paste I cleaned the base of the cooler and noticed what appears to be corrosion on it. It looks like the base is copper-plated, not solid copper, and the plating is missing in some spots.

How important is this? Should I toss the cooler, or consider it a non-problem because thermal paste will fill any gaps?

This is a used Intel cooler which came with a used board. Probably it was new when the board was new, and was left loose with the board when the CPU was removed before the board was sold.

 
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BFG-9000

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That is indeed a solid copper cup pressed into the aluminum slug with tons of pressure.

Copper discolors/tarnishes ridiculously easily so that's normal. If it's cleaned of any surface oil you can press your finger to it and your fingerprint should appear on it just from the salts on your finger. If it bothers you then it could be easily polished off with any metal polish such as chrome cleaner.

Note that using liquid metal thermal interface material (gallium) even once on copper produces a discoloration that is an alloy, which would be considerably harder to remove.

If you wanted a metal that couldn't corrode at all then it would have to be a precious metal such as gold or platinum, which wouldn't make a very good heatsink. Diamond would, but is not a metal.

Silver makes an even better heatsink than copper (they used to sell heatsinks with a silver disc on the bottom) but corrodes even more easily. Silver has the very odd property of the unattractive corrosion being more electrically conductive than the pure metal.
 

BFG-9000

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That is indeed a solid copper cup pressed into the aluminum slug with tons of pressure.

Copper discolors/tarnishes ridiculously easily so that's normal. If it's cleaned of any surface oil you can press your finger to it and your fingerprint should appear on it just from the salts on your finger. If it bothers you then it could be easily polished off with any metal polish such as chrome cleaner.

Note that using liquid metal thermal interface material (gallium) even once on copper produces a discoloration that is an alloy, which would be considerably harder to remove.

If you wanted a metal that couldn't corrode at all then it would have to be a precious metal such as gold or platinum, which wouldn't make a very good heatsink. Diamond would, but is not a metal.

Silver makes an even better heatsink than copper (they used to sell heatsinks with a silver disc on the bottom) but corrodes even more easily. Silver has the very odd property of the unattractive corrosion being more electrically conductive than the pure metal.
 

jhsachs

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SkyNetRising, it's an i7-3770. I've never known performance to be an issue with Intel coolers, although I know they're cheaply built. If this is a serious thing I have a better cooler somewhere, but can you and/or others tell me a bit more about this before I dig it out?

I'm not convinced that the spots in the picture are tarnishing because I can feel them when I run my fingertip over the surface. But they're very faint and I might be imagining it.

BTW, I have an additional question to ask while I'm here. Although I've done this before it's an every-few-years thing, and I'm trying to follow reliable instructions. Intel says to use a blob of paste "roughly the size of a grain of rice or a pea." Other sources are equally vague. I'd estimate that a grain of rice (short-grain white rice) has 20% of the volume of a small pea, or 10% of a large pea! Can anyone give more precise advice?
 
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SkyNetRising, it's an i7-3770. I've never known performance to be an issue with Intel coolers, can you and/or others tell me a bit more about this before I dig it out?
With Intel stock cooler expect high temperatures, thermal throttling on high load and high noise.
CM Hyper 212 Evo or Gammaxx 400 would be good/inexpensive option for 3rd gen i7.
I'm trying to follow reliable instructions. Intel says to use a blob of paste "roughly the size of a grain of rice or a pea."
Can anyone give more precise advice?
You may want to watch this:

View: https://www.youtube.com/watch?v=r2MEAnZ3swQ
 
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jhsachs

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@SkyNetRising, thank you -- the video did solve the problem. Lots of extra talk -- most people who make YouTuboid videos love to chatter -- but the 15 seconds of information I needed were there.

I pulled out my other cooler, a Cooler Master Hyper 212, and found that one metric nut was missing. Replacements are on the way.
 

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