Dunno if you could use the plastic backplate but the Ninja comes with a metal backplate.

Just bought a 430 watt NeoHE a3 and using it with a a8n-e, p180 case with all fans installed and at lowest speed, geforce 7600gs passive cooled and oc'd and amd stock cooler, works perfectly
Though i hope it will be the same when i replace the cpu cooler+ mobo cooler for passive heatsinks