I have heard several times that plugging in high draw fans can wreck the fan headers, but I've never seen it tested or proven. I've also never looked for such info either. A quick google would solve that I'm sure.
Originally Posted by dragosmp
Some people seem to say the max power draw is around .52 amps on the +12V rail, which amounts to around 6W. I wouldn't put more than 6W on those headers as you risk damaging your mobo; you can simply connect a high power fan on a MOLEX connector which can provide a lot more than 6W.
Originally Posted by DuckieHo
Each motherboard has different individual fan header ratings AND total header ratings. Plugging a high-speed fan into an underpowered header may burn out the header completely.
Performance fans are generally used to cool radiators and CPU coolers. Keep in mind that connecting these performance fans to your motherboard is generally a bad idea as they may pull too much power and fry your motherboard's fan header. (Check your motherboard user manual for exact specification ranges)