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Re: [K12OSN] Too weird for words - Epia-V mobo problem and solution



This correlates well with my experimentation and the tech specs for the mobo - the lowest 12V current draw they claim for the board is 119mA. I have a fan that draws about 95mA, and plugging it into the board works in most cases. My 100ohm resistor (which draws 120mA) works in all cases. I'm going to be building 50ohm loads to guarantee I'm always over the minimum. The resistor is a 15 watt (but only 8 if not used with a heat sink) so my 2.88 watt load should be no problem.

I think we've probably bored enough folks with this now. At least if anyone else tries to build terminals with a similar setup, they'll have a *very* complete answer in the archives :)

Rick Barnich wrote:

My experience with the VIA boards is that they don't draw enough current
on the +12VDC line to satisfy the power supply requirements. On many
145-200 watt supplies, the the 12 VDC current spec is 200ma. min. On
many ATX power supplies, the +12VDC output is unregulated and with no
load, the voltage exceeds the limits allowed by onboard voltage
monitoring circuitry. That's why a 3.5" hdd will usually allow the power
supply to start, and a 2.5" hdd won't. On some supplies, I've removed
resistors in the 12VDC sensing circuit, effectively disabling the 12VDC
sense circuitry. This tends to be power supply specific. For 200ma., you
need a 2.5 watt, 60 ohm resistor. Now you're dissapating almost as much
as the CPU!


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Chris Hobbs       Silver Valley Unified School District
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