"Too small" power supply cause wireless PCI card to fail?


O

ohaya

Hi,

One of my PCs went dead last week, and I happen to have a spare Antec
450 power supply, so, to diaganose the problem, I put the Antec PSU into
the PC.

Thankfully, the PC powered up after I replaced the PSU with the Antec,
but, I have a Dynex wireless PCI adapter, and that didn't work. I was
able to get the wireless adapter to work once, by uninstalling the
adapter in Device Manager, and then re-installing and rebooting, but
then, the card disappeared completely from Device Manager, and I can't
seem to get it to appear again.

I know that this is probably a difficult question to answer, but I was
wondering if, for some reason, wireless PCI adapters are particularly
susceptible to having a too weak power supply?

Thanks,
Jim
 
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O

ohaya

philo said:
No, the cards do not require anything special in the way of a power
supply...your card is probably just plain bad


Philo,

That's what I would have thought. Also, I checked specs for the Dynex
PCI card, and it only uses 250-510mA @ 3.3V.

Anyway, I just realized after posting my original msg that I had several
USB hard drives plugged in, and so I figured that I'd try running the PC
without both of them plugged in, and, guess what?

Yep. As soon as I did that, and rebooted the system, Windows detected
the Dynex PCI card again, and it's working now!

So, it seems like the spare power supply I put in is probably really
marginal.

I have another, different spare PSU, an Antec Earthpower 500 PSU, that
my son brought over yesterday, so I'm going to try to swap that in tonight.

Thanks,
Jim
 
O

ohaya

Bob said:
ohaya> Anyway, I just realized after posting my original msg that
ohaya> I had several USB hard drives plugged in, and so I figured
ohaya> that I'd try running the PC without both of them plugged
ohaya> in, and, guess what?

ohaya> Yep. As soon as I did that, and rebooted the system,
ohaya> Windows detected the Dynex PCI card again, and it's working
ohaya> now!

ohaya> So, it seems like the spare power supply I put in is
ohaya> probably really marginal.

I think your OS is marginal. Windows gets confused at the slightest
excuse.


Bob (et al),

Well, I got the Antec 500 PSU installed last night, and the wifi PCI
card is back to not showing up again, even with the two external drives
not plugged in.

I'm really starting to think that the PCI card may just be plain bad at
this point. This whole thing started when the original PSU went dead
one morning when I powered up the system (was working fine the night
before), so I'm thinking something happened over night that "zapped"
both the PSU and, probably, that wifi card.

I have another system that I can try to put the wifi card into, to see
if it works there when I have some free time, so we'll see, I guess...

Thanks,
Jim
 
W

westom

I'm really starting to think that the PCI card may just be plain bad at
this point.  This whole thing started when the original PSU went dead
one morning when I powered up the system (was working fine the night
before), so I'm thinking something happened over night that "zapped"
both the PSU and, probably, that wifi card.

Motherboard could have insufficient bypass capacitors (which are not
related to the power supply). Change the load and that defect (that
remains) is temporarily not apparent. Furthermore, a perfectly good
power supply can fail in some systems. And a defective power supply
can still boot some computers. Just more reasons why swapping leave
you still confused.

Is the power supply defective? Numbers from a multimeter when the
computer applies a maximum load would result in a useful answer. A
simple task that almost anyone can do. Anything else is only
speculation. Maybe a measurement of the 3.3 volts on the wireless
card would have exposed a problem; but this is probably too complex
for most to try.

If a power supply created the problem, only a multimeter would have
identified it. And probably could have identified that problem even
months ago. If anything like USB devices or WiFi adds enough load to
create failure, then the power supply was always undersized even
without that load. And the meter could have identified it.

Failing bypass capacitors would be another and a more likely
reason. WiFi manufacturer's diagnostics might have reported something
useful; especially when used in conjunction with heat. But it sounds
like your choice is to keep replacing parts until something starts
working again.

Why would something fail? Most often a manufacturing defect (ie
bypass capacitors) is especially apparent when a design (ie
motherboard) is marginal. Swapping parts for marginal or intermittent
problems typically creates much confusion. Smarter is to use
diagnositic procedures that give definitive answers.
 
S

SteveH

westom said:
Motherboard could have insufficient bypass capacitors (which are not
related to the power supply). Change the load and that defect (that
remains) is temporarily not apparent. Furthermore, a perfectly good
power supply can fail in some systems. And a defective power supply
can still boot some computers. Just more reasons why swapping leave
you still confused.

Is the power supply defective? Numbers from a multimeter when the
computer applies a maximum load would result in a useful answer. A
simple task that almost anyone can do. Anything else is only
speculation. Maybe a measurement of the 3.3 volts on the wireless
card would have exposed a problem; but this is probably too complex
for most to try.

If a power supply created the problem, only a multimeter would have
identified it. And probably could have identified that problem even
months ago. If anything like USB devices or WiFi adds enough load to
create failure, then the power supply was always undersized even
without that load. And the meter could have identified it.


You don't give up, do ya?
 
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M

Marty

I'm really starting to think that the PCI card may just be plain bad at
this point. This whole thing started when the original PSU went dead
one morning when I powered up the system (was working fine the night
before), so I'm thinking something happened over night that "zapped"
both the PSU and, probably, that wifi card.

Sometimes the mechanical location of PCI cards into their slots is just
plain dodgy. I have seen PCI cards with PCB lands which are very narrow.
Mechanical location problems can be exacerbated by a flimsy computer case
which flexes enough to put strain on the PCI card and move it just enough
enough to stop it working. I have a machine with an Audigy 2 PCI card
just like that. I dare not move the machine because usually after moving
it the Audigy card stops working.
 
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