Researching PCI Express Riser Cards

When I take my Luggable PC (Mark I) around, I sometimes attract attention from like-minded PC builders who look over what I’ve done and offer helpful suggestions. I’m incorporating the Greatest Hits into construction of Mark II. We’ve covered two of them already: (1) Use a Mini-ITX motherboard and (2) use a smaller power supply. Now let’s cover (3) Use a PCI Express riser or extension.

The motivation comes from the fact standard PCI-Express GPU placement is very inconvenient for compact packaging. The motherboard and the GPU are placed at right angles to each other taking up tremendous amount of space. In Mark I I packaged components around the GPU the best I can, but it was far from ideal.

selectcards
Block layout for Luggable PC Mark I, with the GPU inconveniently standing straight up in the middle of everything.

We need more freedom to rearrange these components and that can only come from putting in an intermediary between the PCI Express slot on the motherboard and the GPU connector tab, something that changes the nature of the connection.

First option is a PCI riser card like this unit on Amazon. It gives us a 90-degree turn which is commonly used in servers to fit cards within a rack-mounted enclosure. Rack-mounted servers don’t usually need powerful GPUs, so these customers don’t run into the problem we have: Full power GPUs are two slots wide, the turn means it can only be used at the very edge of the motherboard or else the card will collide with the motherboard. For Mini-ITX boards, this presents an additional challenge because the GPU’s metal bracket, when turned 90 degrees and inserted to the one and only slot on a Mini-ITX board, will also run into the motherboard ports back plate.

Since a simple riser card wouldn’t work for this project, let’s look at extension cables next.

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