I zip tied the PCIe cable where it splits to make it neater I was not sure if that would impact performance if it was too tight+1^
Low voltage, no. Wire insulation damage, possibly. But it would take a lot of tightening tension to even do that. Might have to use pliers to draw up the tie wrap tight enough to damage the insulation or break the stranded copper wire. Which PSU cable are you talking about?
And there are no dumb questions, only dumb answers.