Other than custom cables made to perfect length, no. That spot beside the PSU is where you tuck all the excess cables, which you've already done. Long cables in a small space always mean more stuffing than tidying. As you'll have realized, the USB/Power etc connections on the side panel don't help, as enough flex has to be allowed on those cables. Would have been a nice touch if the connections were isolated from the side panel, and the side panel had a little cut-out for them to fit through.