NYRAD, you can swap the position of the lowest exit tube on GPUs: it's wayy to long the way it is (and way to bendy !). I would go parallel on the dual cards, and use both upper connections for in and out. Or if you really want serial, enter on top right on upper card (instead of top left right now), and exit on top left from lower card. You'll gain a lot of tubing length, and remove a 180° bend.