Weak 12V2 cause power problems? (was "RE: [Pc_Support] PSU quality review")

[Jason Boxman]

Derek Konigsberg said:
> I once had issues in a server of mine where I had a CD-ROM drive, a DLT
> drive, and a bunch of hard drives.  It seemed like the power supply
> couldn't handle the CD-ROM and DLT tape drives at the same time.  (one
> would act funny when the other was in active use)  However, swapping out
> for a power supply with a much better rating on the 12V rail did fix the
> problem.
>
> One thing I've noticed is that most PC-style power supplies love to put
> all their extra wattage into whatever 5V or 3.3V output is used by the
> CPU/motherboard.  As such, your 450W "for that fancy Pentium 4" power
> supply usually doesn't have any higher of a rating on the 12V rail than
> your average measly 250-300W unit.  You really gotta check the details of
> what power supply you buy for a server, since the "wattage rating" along
> doesn't tell you very much.

Sure true.  Sadly the ratings won't tell you have stable the PSU is at those
voltages.  I'm too cheap to buy a miltimeter and check myself.  Plus, once
you can do that you've already bought the PSU...  I guess you could send it
back.

My favorite PSU issue must've been when I had a Dell PSU that was age old
and like 120W or something, but less than a 200W overall rating, and with 4
120GB ATA disks, if you lightly tapped a molex, a drive would spin down and
back up again rapidly.

It was annoying, at first, as I lost a member of a 3Ware RAID 5 array. 
However, I found that once it resync'd, all my data was single bit corrupt
here and there.  (And rsync to a good copy verified this along with various
data files being corrupt.)  Needless to say, I managed to kill my 3Ware with
a crap PSU.

PSU quality does matter when a $150 logic board is at stake. ;)