XPost: uk.d-i-y
<snip>
The +5VSB rail has limited amperes to offer, and it does not matter
whether the PC is 500 watts or 1500 watts. The rating is typically +5VSB
at 3 amps or so. It is easy to overload that 15 watt source, for a
hobbyist with a lot of pocket change for toys.
Look carefully at such things as "USB bus powered loads" or "USB
charging loads". When the +5VSB shuts off on overload,
it takes out the operation of the PC with it.
Roughly the same behavior occurs on CPU THERMTRIP. Check the standing
CPU temperature with a utility, to see whether it is too hot and the
cooler needs "maintenance". THERMTRIP is roughly 20 degrees above the throttle temperature. The machine would slow down a bit, if it was
getting too hot. Sometimes,
a characteristics smell can tell you that the machine is not all that
happy with how you've been treating it.
(Such machines usually have very slow exhaust fans.)
If a heatsink falls off a CPU, it only takes around two seconds (at full power) to destroy a CPU. This is why THERMTRIP was invented, to stop the event before it toasts the chip.
The thermal protection afforded by "BIOS checks" was not fast enough to
avoid damage. A hardware based scheme was invented to take its place.
This was introduced around the end of the AthlonXP era (when I bought my motherboard for the Athlon at the time, I made sure it had the small 14
pin Attansic chip that switches off the power for that). Later implementations, the signal comes right out of the CPU, to halt the
action and drop the PC instantly. Both AMD and Intel had that signal,
after the importance of protection was recognized.
For some of the (latching) power events, you have to use the switch on
the back of the PC, switch it OFF,
switch it ON, to allow an attempt to start it again.
You can't just push the front button, after it's been dropped on a
serious fault cause. It takes some back button or cord-action, to
recover it.
Paul
Just cross posting because the behaviour described above could very well explain the sudden unexpected drop of the PSU.
Thread in uk.comp.homebuilt about sudden unexplained power off.
Cheers
Dave R
--
AMD FX-6300 in GA-990X-Gaming SLI-CF running Windows 10 x64
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