----- Original Message -----
From: "Christopher Klein" <[EMAIL PROTECTED]>
To: "'The Hardware List'" <hardware@hardwaregroup.com>
Sent: Friday, February 24, 2006 10:56 PM
Subject: RE: [H] Voltages too high?
I don't have a multimeter here...I'd have to bring it in to work. I
don't
remember which PSU I have at this point...I'll have to crack it open and
look. How high is too high?
Your situation helps make my case for hooking any computer to a UPS, not a
wall outlet or surge strip. The AC voltages feeding the power supply can
vary enough to cause your DC output voltages to be out of acceptable
range, low and high. Now if some electrical expert will give us the
percantage of voltage variance that is acceptable, we will have lots more
to work with. My uneducated guess is 10% which would allow the widest
acceptable range for a 12 volt output to be from 10.8 to 13.2. That seems
too wide. 5% seems more realistic, 11.4 to 12.6.
Not quite. Switch mode power supplies used in today's computers use feedback
circuitry to maintain stable output voltages for ordinary input voltage
swings. If the input voltage increases 10%, your output DC voltages will
NOT. If it was a linear supply, then yes, but switch mode supplies just
don't do that.
My SeaSonic S12, for example, is rated to work at ANY voltage between 100
and 240VAC. Not just 110/220, but any voltage between. 179.8v would be fine
for it.
That being said, I too recommend a UPS for any computer. This one is on an
APC SmartUPS 2200VA unit--and all of my machines are on a 550VA or better.
Most are on APC 1250VA units. It doesn't make sense to me to blow $1k on a
computer, and then settle for a $7.99 power/surge strip from Wal-Mart to
protect it.
As far as output tolerances, generally, +/-5% is considered nominal for the
3.3 and 5.0 rails, and +/-10% is nominal for the 12v rail. That leaves a
range of 3.135-3.465v, 4.75-5.25, and 10.8-13.2v. While his +3.3 and +5.0
rails are supposedly beyond that, we won't know anything until a multimeter
is used to determine the real voltages. Onboard sensors are horribly
inaccurate. Even if those numbers are accurate, they still aren't so far off
as to cause a problem.
