My girlfriends awesome budget build in a 2004 OEM case.

[NicolaZanarini]

Well here is what i think you could do to improve it. You are right though non-modular PSUs are a pain to deal with.

 

1. The harness that runs nearly parallel with the drive cage...just making that harness run exactly parallel to the edge will clean it up significantly.

2. On the back, make all the runs as straight as possible. One thing i do is layout routes and group my harnesses on the routes...in your case it may not be possible but give it might.

Yeah, thought about both but point 1 is impossible (the wire is just not long enough) and tried every routing possible short of dissembling the case, lol.

Point 2, as you said, i did to all the harnessing that could be done, but there actually is such little space between the chassis and the frame that I was forced to "spread" the wires out like butter -it barely closes as it is (on the bright side less vibration )