Faulty case fan cause of system instability?

[ShadowTek]

Recently, my computer started freezing and rebooting. I ran memtest and
found errors within a half hour. After testing various components, I
found that no more memtest errors occured after the removal of one of my
case fans, a 23cm, 4-LED fan made by Globe, model RL4B.

I ran memtest for at least several dozen complete passes and no further
errors were detected. About a month has passed since that time, and no
further unexpected system reboots have occured.

Have you ever heard of a faulty case fan causing memtest errors?

The fan's label states that it uses 0.35 amps on the 12 volt. I thought
that maybe the problem was that my PSU wasn't up to the task, but
I loaded each cores of my Core 2 Duo E7500 with burnMMX while stressing my
GeForce 9600GT with repeated timedemos of Nexuiz. I did that for 20 or
30 minutes and there weren't any errors or problems of any kind, so I
don't think the PSU's 12v is faulty.

Could the problem be some sort of electrical problem caused by the LEDs in the
fan?

Just a wild guess.

 

[larry moe 'n curly]

Recently, my computer started freezing and rebooting. I ran memtest and
found errors within a half hour. After testing various components, I
found that no more memtest errors occured after the removal of one of my
case fans, a 23cm, 4-LED fan made by Globe, model RL4B.

I ran memtest for at least several dozen complete passes and no further
errors were detected. About a month has passed since that time, and no
further unexpected system reboots have occured.

Have you ever heard of a faulty case fan causing memtest errors?

The fan's label states that it uses 0.35 amps on the 12 volt. I thought
that maybe the problem was that my PSU wasn't up to the task, but
I loaded each cores of my Core 2 Duo E7500 with burnMMX while stressing my
GeForce 9600GT with repeated timedemos of Nexuiz. I did that for 20 or
30 minutes and there weren't any errors or problems of any kind, so I
don't think the PSU's 12v is faulty.

Could the problem be some sort of electrical problem caused by the LEDs in the
fan?

Fans generate electrical noise from their motors and DC-AC inverters
but not from their LEDs. The fan current draw is neglibile for the
PSU and, BTW, is usually just half the labelled rating. Maybe the
Globe fan doesn't have a filter capacitor across it to block the
noise, or the mobo doesn't have enough filtering at its fan connectors
(most I've looked at had none, just empty spaces where such capacitors
could be installed). Have you tried plugging the CPU fan into the
connector for the case fan (if it's adjustable, test at full speed to
maximize current draw) or the case fan into the CPU fan's connector?
I've seen many mobos where the fan filter capacitors were missing, and
to see if that's the cause of your problem try jamming a 0.1uF ceramic
or 10uF, 25V (or higher voltage) electrolytic in the rear of the fan's
cable connector, between its black ground wire and its red +12V wire
(on 12V fans, red means +12V, not +5V as it does with computer PSUs).
Be sure to get the polarity of any electrolytic cap correct, meaning
the minus side (big stripe running down one side)goes to the black
ground. If this eliminates memory errors, try to make the attachment
permanent by soldering the leads, but even if you don't, at least
cover it with heat shrink tubing or _good_ cloth or plastic tape so it
can't come loose or short something.

 

[ShadowTek]

Fans generate electrical noise from their motors and DC-AC inverters
but not from their LEDs. The fan current draw is neglibile for the
PSU and, BTW, is usually just half the labelled rating. Maybe the
Globe fan doesn't have a filter capacitor across it to block the
noise, or the mobo doesn't have enough filtering at its fan connectors
(most I've looked at had none, just empty spaces where such capacitors
could be installed). Have you tried plugging the CPU fan into the
connector for the case fan (if it's adjustable, test at full speed to
maximize current draw) or the case fan into the CPU fan's connector?

This fan only has a 4-pin molex connector, so it always runs at full
speed.

I tested on one of the PSU's other connectors, but there were still
memtest errors on the other plug as well.

I've seen many mobos where the fan filter capacitors were missing, and
to see if that's the cause of your problem try jamming a 0.1uF ceramic
or 10uF, 25V (or higher voltage) electrolytic in the rear of the fan's
cable connector, between its black ground wire and its red +12V wire
(on 12V fans, red means +12V, not +5V as it does with computer PSUs).
Be sure to get the polarity of any electrolytic cap correct, meaning
the minus side (big stripe running down one side)goes to the black
ground. If this eliminates memory errors, try to make the attachment
permanent by soldering the leads, but even if you don't, at least
cover it with heat shrink tubing or _good_ cloth or plastic tape so it
can't come loose or short something.

I don't have any spare caps on-hand. I'd have to stop by the store
sometime.