Mac Mini... Painted Heatsinks?

[Superdos]

This topic seems to fit in the hardware hacks section... although this is about an Intel mac.

I have a Late 2009 Mac Mini 2.53 I picked up in late 2012 for $100 with a broken hard drive and 2 gigs of RAM. 8GB of Crucial RAM, a 1TB hard drive, and a thermal compound re-paste later, and I had myself a VERY nice little workhorse of a Mini... even if I only turned it on once in a blue moon, moreso after getting the HR Powerbook. Two weeks ago, I took it back apart on a whim and inspected the heatsinks... and I really want to call bull on the "anodized" heatsinks used to cool the P8700 and nForce chipset.

I have reason to believe that they are not anodized, but are lightly painted by the way they shimmer in direct lighting... that is, barely. I have had black anodized aluminum heatsinks in the past and they usually show off a not-black sort of indirect viewing angle sharpie ink-colored shade and shine more than these things do. This would explain the sketchy looking temperatures I get... since paint is a sorry excuse of an anti-corrosion measure and just insulates the heatsink. Can anyone confirm this is the case? Attached picture is an eBay listing pic of the dinky heatsink they put on the nForce that, once it gets hot, starts cooking the hard drive... which is why I wholeheartedly believe this is what caused the original hard drive to fail, and why smcfancontrol continues to be awesome in preventing this from occurring. This seems to be the ONLY Mac mini heatsink AT ALL on ebay. at least, in the US. Someone else is selling a nylon screw kit "for use with the 2006 Intel mac Mini" I may consider if it'll give me just a teensy but more clamping pressure without bending/warping the logic board doing so.

To sort of put it in perspective, I know there have been times in the past Apple did have painted heatsinks on things like the older TiBook G4, and even on the heatsink fins ad part of the heatpipe around the fins of the aluminum Powerbook G4, least in my case.

To remedy my concerns, I'm going to be getting the heatsinks sandblasted to remove the upper coating of whatever it is. an entirely free sandblasting... the only thing I'm paying for in is time allotted before it can even be sandblasted since the guy doing it has to switch to the softer stuff before he can sandblast it, last I heard yesterday.

 

[Elfen]

Paint on a heatsink is not good, as it traps the heat in. Best to get it removed. 

But did you do a scratch test on it? Scratched it with a needle and if its painted, you will scratch it easily. If it is Anodized, it would be harder to do.

 

[TheWhiteFalcon]

The TiBook heatsink shimmers too, I'm not sure there's an issue there.

 

[Byrd]

A thin bit of paint (but I'd assume anodizing) isn't going to impede cooling much; overheating isn't a common issue in Minis.  I think you're going a bit overboard.

 

[Cory5412]

To add, the P8700 is pretty efficient and low-power as Core2Duos go. If I remember correctly, it's a 20 or 25-watt part. (Compare to 35-watt for the i5-3210M in the 2012/Ivy Bridge mini).

It shouldn't really take much to cool it, so even if Apple (mistakenly or intentionally) did something to reduce that cooling ability, it should still be pretty efficient, especially after the paste job you did to it.

I wouldn't worry too hard, as Byrd says, the minis almost never overheat -- and the only reason one of them would is if it were getting old and the paste was never reapplied or it was reapplied incorrectly.

Fortunately, the way it would fail is that the chip would get slow and then shut down before any actual damage was done, giving you warning that it's time to do some maintenance.