Henners. Well the cabling isn't "artwork pretty" but I'm a functional, nobody's gonna see it anyway kinda Old Guy. It's not so bad to start with, but a little tidying and it doesn't look like it would impede airflow. Here's my case cabling, before the GPU and other expansion cards. The GPU does not have a power cable to the PSU so that's not a cabling issue.
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I found that routing behind the tray and also tying cables down behind the tray controls the clutter.
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Have you tested temps with and without the extra two fans inside the lower drive bays? I've wondered if the two fans blowing in and the bottom fan blowing up creates some turbulence that disrupts airflow to the top exhaust fans.