Seasonic S12 / tyan k8e problem

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

[ Apologies to folks that already saw this in the tyan group. -wsr ]

Is anyone here seeing a problem with Tyans and Seasonic power
supplies? I have a new Tyan k8e s2865 that I have attached to a new
Seasonic S12 430 watt unit. 9 out of 10 times when I turn the PS on
at the rear switch the board comes up with "FF", the code for can't
boot/post and the two front pannel soft switches, power and reset are
both totally inoperative. The only way to cycle things is by flipping
the rear switch.

If I flip the rear switch quickly enough, turning it off for only an
instant, I can sometimes "catch it" and the system boots normally and
runs just fine once booted. In fact, I installed redhat fedora
without incident while it was up. It is just the turn on that is

When it is stuck the none of the cpu or mobo-connected case fans are
spinning and I assume the board isn't really powered up fully. The
cpu heatsink doesn't get hot so I assume it isn't really powered on

All the voltages are well within range when the system is stuck. I
measured all of them right at the 24-pin and the 8-pin connectors
while the connector was plugged into the board and displaying FF.

4-pin drive:
red 5.117v
yellow 12.09v

8-pin aux:
yellow 12.09v

24-pin main:
orange 3.271v
yellow 12.08v
blue -12.18v
red 5.116v
green 0.015v /power-on, low == on
purple 5.097v 5v standby
gray 4.947 power-ok, high == ok

This same board runs just fine on an older ESPV12 supply.

The Seasonic looks like a nice 80% efficient, low noise unit with a
universal plug set (24-pin w. both 4-pin and 8-pin CPU aux). I'd hate
to trade if for a noisy 60% efficient ESPV12 supply if possible. I
just wish I could figure out what is going on here. Ideas?

Wolfgang S. Rupprecht
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More about seasonic tyan problem
  1. Did you ever resolve this issue? I have TWO S2865s and they both have the same problem. Different power supplies and they both occasionally stop working and won't boot (FF). I can uninstall them or perhaps leave them disconnected and eventually they boot and may run for months. Seems to be a common component related to reset or power.


    Roland Kretschmann
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