AC fans make no difference with DC fans if you consider performance / noise. Ball bearing/brushless DC motors are silent enough so AC motors (quite silent already) have no edge there.
What you'll end up with AC fans is:
good: No power drain on your PSU
bad: an AC variator is quite bulky and/or difficult to build. Must use a PWM or any 'smart' AC/AC technique... definitely not for the faint hearted.
If PSU power drain is your main concern so go for them, they're even cheaper than their DC counterpart (due to the AC motor). You can find em in the same places where you buy your usual industrial hardware.
Redleader: Look he's from Norway... They've got 230V out there
[ 09-24-2001: Message edited by: SureFoot ]