WE’VE HAD SOME criticism on our original story about the rusty chokes on certain Asus motherboards that got pointed out to us, so we decided to do a follow up. This time around we’ve done what many of the comments around the web have asked for, we cracked one of the chokes open to see what it looks like on the inside.
Many of those that read the story noted that the rust only seemed to be superficial and we agree that it was hard to tell where it came from, in part due to the clear coating on the chokes. We had one of the chokes from one of the 12-phase boards de-soldered as you can see on the picture below. The chokes are clearly labelled C.S and from what we’ve been told, this is a brand exclusively used by Asus on some of its motherboards.
The coating on the outside came clean off when the choke was cracked opened and from this picture it looks like most of the rust is attached to it rather than the choke.
However, if you take a closer look at the picture below, you’ll notice that however strange it may seem, the copper coil inside the choke is coated in rust. As far as we know, copper can’t rust.
It’s even clearer in the next picture and this is something we can’t explain. Copper normally corrodes over time or with the additional help of moisture, but never rust. Normally copper wire is coated to prevent this from happening in electronics which makes this mystery even stranger.
Here’s a picture from a slightly different angle showing more of the rust on the copper coil. It’s quite obvious that this is something that shouldn’t be able to happen, despite the somewhat porous structure of the iron powder around the copper coil.
Finally we have a picture with the coil from slightly different type of choke (which has been in use for about six months) next to the rusty choke for comparison.
One thing that’s obvious from the pictures is that there isn’t a huge amount of rust inside the chokes, with the exception of the rust that attached itself to the coil. We wish we had a good explanation as to what has gone wrong here, but this really is highly unusual. Something has pretty obviously gone wrong in the manufacturing process, but until we get a statement from Asus, we just can’t provide a clearer answer.
The question is will the chokes continue to deteriorate over time? And how will this affect the power regulation circuitry on the motherboard? These are answers we don’t have and only time can provide the answers. We’re somewhat surprised that we haven’t heard anything from Asus on this matter, since if we owned one of the affected products we’d want to know if it is covered by warranty and what Asus is doing to rectify the problem. If and when we hear from Asus, we’ll post an update.S|A
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