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.
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Which will result in the fan being full-speed all of the time.
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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. |
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You can get a fan controller for about $20. Or rewire a molex to 7 or 9 volts.
Originally Posted by auricgoldfinger Which will result in the fan being full-speed all of the time.
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Worse.
Motherboard fan headers are not 100 percent independently power, there are other things on the motherboard that are powered off what I assume is a similar circuit. I tried powering a fan off my roommates computer (mid-range Asus motherboard, Silverstone PSU) and in doing so a stick of RAM was toasted. I assume in some part drawing too much power or something. Also, fans that are rated for 12v 1.0A can draw more when first starting up.
Rule of thumb: 120x38mm fans should almost always be powered off molex, 120x25mm should can be either. Also, if the fan is a high-speed server fan, don't run it off the motherboard. If they fan specifically has the standard motherboard header tail, and you bought it from a reputable store, then it should be fine running off a motherboard.
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. |
Motherboard fan headers are not 100 percent independently power, there are other things on the motherboard that are powered off what I assume is a similar circuit. I tried powering a fan off my roommates computer (mid-range Asus motherboard, Silverstone PSU) and in doing so a stick of RAM was toasted. I assume in some part drawing too much power or something. Also, fans that are rated for 12v 1.0A can draw more when first starting up.
Rule of thumb: 120x38mm fans should almost always be powered off molex, 120x25mm should can be either. Also, if the fan is a high-speed server fan, don't run it off the motherboard. If they fan specifically has the standard motherboard header tail, and you bought it from a reputable store, then it should be fine running off a motherboard.
I'm not sure, but I plugged in a 120mm fan and it ran on high for a while. One day, I noticed my computer was very sluggish, and I looked in the case, and teh fan wasn't spinning. That header is now dead.
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