thanks, Busta.
I was afraid the minimum 7v required is a must or the fan don't spin at all, albeit lower speed.
My Sunon spins 1900-2000 rpm @ 5v and it's mostly the hd noise I hear. Good enough for surfing @ 26C/26C, 19.6C room temp.
I'm not using the mb 12v line at all, just the speed sensor and ground cpu fan to mb header. Sensor don't work unless fan is grounded to mb. Fan alarm still works this way. 5/12v supplied my 4pin ps molex via switch.
Will I still burn my mb header this way? This is my last one. Done burn two already due to careless wiring.