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Power supply fan shuts off, M2N-SLI-Deluxe

H

Henderson

Member
This system was put together almost 2 months ago. A few days ago I noticed the green LED light for power wasn't on and the power supply fan wasn't turning. On reboot I could hear the power supply fan turning on momentarily, and then turning off while the computer booted up.

The computer boots up just fine though and everything runs perfectly without any issues at all. I've replaced the power supply with a new one (same model, Neopower 650), and it's definitely not a defective p/s, the fan does exactly the same thing... turns on momentarily and then shuts off. It never comes back on.

PCProbe indicates the power supply fan not turning of course, all other temps and fans are fine. There's no other errors or problems anywhere running any application or game, there's also nothing in the Device Manager indicating any problems. CPU fan and case fans all work as they should. There's no overheating at all since I usually keep my cases open and other fans seem more than adequate as I leave my PCs on 24/7 and it's still not overheating without the p/s fan.

System specs:
M2N-SLI-Deluxe
AMD Athlon 64 X2 6000
Antec NeoPower 650W power supply (replaced with new one today)
4 GB Corsair DDR2 ram
PNY 8800 GT video card
2 - 400 GB hard drives
2 - DVD-RW drives
WinXP Pro with all current updates

What else I've done with no help:
- Set the bios to default settings, no change.
- Upgraded bios from 1405 to 1502, no change.
- Checked all connections inside the case, nothing amiss there.
- Started PC up with a linux disc, same problem of no power supply fan.
- Booted up on a 2nd cloned drive that I keep as a backup, maybe 4 weeks old (no WinXP updates), no change.
- Booted up in safe mode, no change.
- New power supply as mentioned above, no change.

There were no hardware changes at all before this happened. The only program changes were a new DVDFab upgrade, and some WinXP updates, including SP3. The system has never been overclocked at all. AV is Kaspersky 7 kept current, spyware/malware is scanned for several times a week with Spybot, Ad-aware and Xoftspy. Cool and Quiet nor Q Fan have never been enabled on the motherboard.

Could this still possibly be some setting somewhere causing the fan to shut off? Bad motherboard? I'm stuck on this one.

Would really appreciate any suggestions, thanks.
 
Its probably a thermally controlled fan. It doesn't come on unless it gets to a certain temp.

"Low-speed 80mm fan delivers whisper-quiet cooling and ensures quiet operation by varying fan speed in response to load and conditions"

I'm not 100% sure but I used to have that same problem and somewhere I found out that that fan wasn't supposed to come on (and I rarely saw it come on) unless it got hot. I'll gladly take that "defective" one off your hands 🙂

It probably momentarily spins up when you first power on and then back down, kind of like a cpu or vga fan. I'm not sure though. I wonder if it has anything to do with the 3 pin fan speed controller. I never quite understand what the deal with those are on power supplies. If anyone knows, please chime in!

Also, as to why your power led is not on, its probably a coincidence. If you have the polarity reversed the led wont work. I don't believe that the two problems are related, but if they were then it would have to be some freak problem with your motherboard.
 
If it was a normal function of the fan, sooner or later the fan would have to turn on, especially during the summer heat (I don't have AC in the room with the computers). I've been keeping PCProbe running to monitor it, and the fan in the power supply *never* comes on, it stays at 0 rpm. Today is warmer than usual and the alarm went off for the motherboard temp rising, and the fan still didn't come on. To be safe, I just set a table fan to blow into the case to stop that.

I don't have one of the 3 pin connectors on the power supply, have never seen one on an Antec. There is a place on the motherboard for a 3 pin "pwr_fan" which I hooked up with a spare connector off another fan, and it did nothing different... power supply fan remained off.

The green LED light worked before, and no one but me touches the computers to have pulled the connection and reversed it. I swapped the connectors and hooked up the green LED to the HD light, and the green LED does work. Just not with the Power switch connected to it. The usual HD LED did not light up as the power switch though.

It's possible the power supply fan has been out much longer, but I think I would have seen some signs of overheating during the hotter days, and I haven't. But I'm thinking the two are related though.
 
The name of the 3 pin wire I'm thinking of is "fan-only output." I've had it on Antec Smart Power psu's in the past. I think all it does is when you hook it to the board you can control the fan speed along with the other fans in the case via built in fan speed controllers. I'm not sure how PC Probe would know that the psu fan is not spinning without the aforementioned fan-only output which can vary the voltage to change the fan speed. I was under the impression that the fans in those psu's like you have would vary fan speed based on the ambient air temp of the case.

I'm confused about the power switch / green led connection. Why do you have led attached to the power switch? The power led and the power switch are different pins on the front panel header pins. It doesn't matter which way you wire the power switch but it does matter which way you wire the led's. I'm sure you already know that though.
 
I only swapped the LED connectors around to rule out that it was simply a defective LED. They are wired correctly though since the green LED light always was on before whenever the PC was on.

And now that you brought it up, I'm not sure how PCProbe knows the speed of the power fan without that extra 3 pin connection, but it always did in the bios and in PCProbe. It's unmistakable when it's not working, the indicator is red instead of green.

Since this happened I've also been checking the fan from the back quite often to see/feel that there's no air movement whatsoever from the fan in the power supply. The fan never turns on however other than the brief few seconds when the computer is first turned on.

Before I through the hassle of returning the motherboard, I just want to be sure I rule everything else out.
 
I'd really check into the quiet fan feature of the antec psu. Its probably how its supposed to function. I had the same situation with you did with being worried about the non-moving fan in antec psu and antec said that this is how it was supposed to be. I might be wrong but it just seems fishy that 2 psu's do the same thing, and normally the mobo has no control over the fan speed. I don't believe any pins on the 24 pin connector are correlated with fan control on the psu.

Maybe fire up that 8800gt and turn all the settings up, try to get the system heated up and that fan will turn on.
 
I have a NeoPower 550W installed in my 2nd PC so turned on PC Probe and watching its behavior. While the rpms will fluctuate as the system does more and heats up more, it never shuts off completely.

Last night while playing an online game, PC Probe went off that the motherboard temp was rising. It still didn't turn the power supply fan on though, it stayed at 0 rpm and I could see no fan movement. I have a desktop fan now blowing into the case so I don't blow out anything else.

I played around with turning Q Fan on also, no change. The power supply fan obviously is monitored through either the 24 pin or separate 4 pin connector to the motherboard since the 2nd PC with the NeoPower 550W indicates the power supply fan rpms without any special hookup.
 
Good idea to call Antec just as another double check, which I did this morning before calling Asus. Antec said there's no program or setting that would totally shut off the fan in the power supply. They also confirmed that the Neopower will vary the fan speed, but will never totally shut off the fan. He asked about upgrading the bios, which I had done, so he was pretty certain it had to be the motherboard as well since two power supplies were doing the same exact thing.

Called Asus and they issued an RMA. They really had no input other than ruling out the power supply. Once I get the new board in, I'll post here that it hopefully has cleared up the issue.

Thanks for the help.
 
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