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Old November 11th 10, 02:54 PM posted to alt.comp.hardware.pc-homebuilt
Paul
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Posts: 13,364
Default Building mame box

henry21 wrote:
Could I just continue to use the 12v from the motherboard system fan
source? This is only 1-2 amp I think? This is working now, I am just
ignoring the white sense connector.

Thanks.


Fan headers have a current limit. Some retail motherboards, in the
user manual, will tell you how much current you can safely draw.
Exceeding the number by a large amount, will burn out a copper
track in the motherboard. The fan headers are *not* protected
by a fuse. The motherboard has fuses on USB ports and on PS/2,
but there are never fuses on the fan headers. They're an accident
waiting to happen.

That's why, getting your power from a Molex 1x4 disk connector, is
a lot safer. The Molex pins are good to about 8 amps or so.
They'll burn eventually, if abused (I've had to replace one here),
but they'll take a lot more current than a fan header.

Paul