So i bought my P5 yesterday, spent all day/night playing with different setups; and then hit the riser issue. I'm an engineer so naturally curious i researched into the plausible reasons it was so unreliable. Mine worked then didn't then did etc.
After using a ferrite core which was supposed to be at the range of 85ohm (the working cables impedance) and then using really thick double layered aluminium tape, then heat shrinked; i re-ran through everything again, with 0 luck.
I decided to take ALL the shielding off of the cable to see the condition of the ribbon cable, and this is the actual manufacturers of the cable:
EDIT: This is the one i'm buying tomorrow to fix the issue. $118 Aud..
more so; not sure if mine was a one-off but my actual cable shielding coming from the header (really thin film) was under the adhesive used for the shielding. It could be conductive adhesive used, but most aren't that i've seen. Kinda explains why it was so dodgy.
I've stripped mine down and will reflow the headers to seat everything nicer, and re shield and test, also ground to mobo ground.
oh and hi; first post haha
Edit: Stripped the jumper, last 4 pins were completely snapped 1/2 way into the header. Disassembly was done via rework station at low heat and low air flow also