[wellylug] OT: 4.6V on the 5V rail is indicative of....?
Wood Brent
pcreso at pcreso.com
Mon Mar 29 09:40:58 NZST 2004
--- Damon Lynch <damon at photo.geek.nz> wrote:
> Hi,
>
> Apologies if this is too off-topic. If a motherboard is indicating it
> is getting only 4.6V instead of 5V, is this generally caused by the
> power supply unit failing to deliver the needed power? And if so, is
> that something that occasionally happens to a PSU, or should I be
> looking into the quality of the power coming out of the wall power
> socket (it's a 1930s house)? It sure makes the PC unstable!
Running Linux on a PC without a PS is tricky, so I figure it is not totally
off-topic :-)
General rule of thumb, most systems generally tolerate at most about +-10% on
any particular rail. You are 0.4v down on a 5v rail, so are intside this
guideline, but close enough to suggest it is a bit marginal. IMHO, the mains
voltage is unlikely to have much impact on this, it is more likely a quality
issue with your switched-mode PC power supply, & throwing a new one at it
should fix the voltage problem.
Also, how sure are you that this low voltage/PS is the cause of the
instability?
Occasionally some flaky motherboard or hard drive, or a heavily spec'd system
can draw more current than the PS is designed to provide on a given rail, which
can show a low voltage rail as a symptom.
Like many things, you generally get what you pay for. Cheap ATX power supplies
are generally OK, but not as likely to have the reliability, stability,
tolerances, low noise, longevity, etc of more expensive ones.
I can lend you a PS if you wanna see if the problem goes away, before you rush
out & buy a new one??
Brent
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