connecting 24w fan to motherboard

Ive go a delta 120mm fan for my heatsink and I was wondering if it would be safe to connect to my a8n sli deluxe. The fan is a 12v fan and draws 24watts at 2amps. In the manual this is the maximum the motherboard can take. Would it be safe to connect this? I was thinking that if the 12v fluctuates then more than 24watts could be drawn from the motherboard. Is there any chance it would damage the motherboard?
If this is a no go does anyone know of a fan controller than can support this. I need some way of varying the speed.
info at

http://www.delta.com.tw/products/dcf...FB12012038.pdf

fan is the 12v 4000rpm

Regards,

Brian

I reckon it's probably better to play it safe and connect it straight to your power supply.