Random panics on new hardware

Matt Dawson matt at mattsnetwork.co.uk
Wed Apr 28 12:33:08 BST 2004


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Dimitrios wrote:
> My currentl dual athlon runs 6 ibm ultrastar U160 scsi drives
> with loads of extras (usb devices, cdroms, cdrws, dual ethernet)
> and its running on a single Enermax 450W with the 3.3V rail
> running at ~3.2V (the 5V is not really important any more,
> and not used in most modern systems, the 3.3V is the important one).

Bit of a false statement, that. The 5V rail runs all your drives' logic (an=
d=20
some motors, although that is officially the 12V rail's job since it can=20
supply more power for an equal conductor diameter at the same current),=20
powers the USB ports and is the source for many of the mobo derived regulat=
ed=20
voltages. It is also the only rail supplied when the PSU is "off" to enable=
=20
an ATX board to switch the power supply to operational mode. The 5V rail ma=
y=20
be more important than you think.

Getting back to the point, I had a similar argument with a nameless supplie=
r=20
and importer of cases whilst I was working as a production manager for a ye=
t=20
again nameless PC manufacturer.=20

The PSUs they supplied were ostensibly 250W (yes, it really was that long=20
ago), but a quick calculation from the specs actually printed on the PSU of=
=20
voltages and currents (VxI=3DW, rather simple even for a sales droid at a c=
ase=20
importer to understand) showed they could only supply 164W absolute maximum=
=20
full tilt. Eventually I had them all returned and demanded the correct=20
specification power supply to be sent.=20

The problem? The PCs we were supplying were all failing "lights out" with a=
=20
large and unnerving bang after about three months (and many BSODs) due to P=
SU=20
overload and it was costing us a fortune to send an engineer with a van ful=
l=20
of PSUs to relace them all. We eventually got some decent PSUs, but=20
unfortunately this practice of over specifying poor hardware is rife in the=
=20
industry and goes largely unnoticed. No wonder some of the smaller PC house=
s=20
get a bad reputation for reliability with this sort of thing going on. Why =
is=20
the computer industry the only one that sees this sort of thing as acceptab=
le=20
behavior?

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Matt Dawson.
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