sharing the art of SAS cable folding... in a Supermicro 846

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BLinux

cat lover server enthusiast
Jul 7, 2016
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a while ago, as I was building my first Supermicro 846 system, i asked the question about how best to run cables to the PCI-E slots without blocking air flow to the HBA:

https://forums.servethehome.com/ind...o-846-cooling-of-pci-e-hba-controllers.15466/

I have since come up with what I think is a very clean way to route SAS cables in the 846 that doesn't hinder the air flow over the PCI-E slots. Someone posted to my previous thread today, which reminded me I should share.

So, when I first started this project, this is how I routed the cables to the HBA:

CableFolding0.jpg

As you can see, the cables sort of created a "wall" that didn't do much good for air flow, especially considering the heatsink is on the other side of that wall. In the previous thread, @Terry Kennedy posted some pictures of how he twisted those flat cables, which was what I was going to do until I had another idea:

CableFolding1.jpg

CableFolding2.jpg

CableFolding3.jpg

CableFolding4.jpg

CableFolding5.jpg

As you can see, by folding the SAS cables as I did in the photos, they completely sit beneath the fans in front of the fan wall, and on the PCI-E side, they are completely out of the way of air flow.

Some tips regarding the "art of SAS cable folding" :
1) don't always take the shortest route
2) orientation matters; as the SFF-8087 connector has an orientation, it may not end up in the right orientation where you want to plug it in. if you run into that, watch the photos for how i "doubled back" before folding a 90 degree turn.
3) alternate folds; the ribbon SAS cables are actually 2 ribbons on top of each other. every time you fold, the ribbon on the inside of the fold gets longer since it traveled less to make the fold. if you keep folding in the same direction, you'll end up with 1 of the 2 ribbons having too much excess, therefor, alternate the folds whenever possible to even things out. if you can't, like the upside down "U" shape above the PCI-E slots, take advantage of 90-degree folds; every 90-degree fold can be made in 2 different ways so if you've had to fold in one direction twice, use the 90-degree fold to fold the other way to "even" the ribbons out.
4) practice with long strip of thick construction paper; the cables are wrapped in a foil and it leaves behind crinkles when you try to 'unfold' a previous fold. so cut out some long strips of thick construction paper to figure out how you want to fold before you start folding the actual cable.

I really liked how this turned out. Not only does it accomplish my objective of getting out of the way of air flow, when I unplug the SAS connectors from the HBAs, they sort of just "sit" there and don't fall on to the motherboard, which makes it convenient and nicer to handle.

Anyway, just thought I'd share the idea for anyone else who might be trying to use this fold-able ribbon cables...