Well, this is driving me nuts... All of a sudden this morning ASUS probe starts beeping to me that the power supply fan is cutting in and out. It has 2 visible fans, and both seemed to be operational, but rather than turn off the ps fan monitor I started fiddling... First thing I noticed was that if I removed the case cover the beeping stopped permanently. Put it back on, and the alarm would sound intermittently. So for fun I disconnected it from the 3 pin MB header. The power supply fans kept running (evidently, they're not taking their current from there), but right around that time my FRONT chassis fan, connected to the other 3 pin header stopped spinning, which ASUS probe reported accurately. Since then I've been unable to make a "standalone" fan spin when connected to either the 3 pin PS or chassis fan headers. The power supply fans run whether or not it's connected to a 3-pin, but of course ASUS Probe won't report RPM if it's not. The CPU fan is fine. I can plug any 12V fan in there and it spins up. But plug one into either of the other 3-pin headers and ... nothing. This really bugs me, since it suggests a short of some kind, but I had the whole thing apart and just couldn't find a thing. Does anyone have any ideas on what I might look for, or any ideas in general? Unfortunately I have the whole thing back together, running without one of its fans, and if I have to disassemble it again I'll be bumming, but ... so be it. Does this make any sense at all? The machine is running fine otherwise. P4C800-E Deluxe, 3.0GHz P4, 1 GB (HT), 2 120GB SATA/Raid 0 ... anything else you need to know, please ask. Thanks.
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No 12V to chassis and ps fan headers on P4C800-E
- Thread starter rmusgrove
- Start date
chriseubank
MIS
If I'm not mistaken, the power supply fan is actually mounted physically INSIDE your power supply.
By the sound of this intermittent behavior, I'd suspect your power supply is on its way out the door unless you're really confident soldering around high voltage capacitors (inside the power supply).
Removing the case panel and having the fan stop beeping doesn't make too much sense, unless the dust building up inside the case is so bad that it's interfering with the rotation of the fan blades inside the power supply unit. IN that case, opening the cover may increase air flow somewhat allowing the blades to spin more freely? who knows!
HTH,
C
By the sound of this intermittent behavior, I'd suspect your power supply is on its way out the door unless you're really confident soldering around high voltage capacitors (inside the power supply).
Removing the case panel and having the fan stop beeping doesn't make too much sense, unless the dust building up inside the case is so bad that it's interfering with the rotation of the fan blades inside the power supply unit. IN that case, opening the cover may increase air flow somewhat allowing the blades to spin more freely? who knows!
HTH,
C
- Thread starter
- #3
Yes, C, the PS fans are inside the PS. But the MB has a 3-pin header labeled "PS Fan", and the PS has a 3-pin connector that fits there. What I think I've learned is that this is only used for the MB to monitor the PS fan RPM, not to provide power to it. At least this particular PS doesn't require it. Furthermore, the PS fans ARE operational, and always have been. The problem began with the ASUS motherboard monitor inaccurately (?) reporting that they were NOT running. When I started fiddling to try to correct this is when the *real* problem started, which is that my front CHASSIS fan has stopped spinning, and it's not the "fan" that's the problem. It's that there's no power coming from the 3 pin header on the MB labeled "chassis fan". Nor is there any coming from the one labeled "PS Fan", which there should be, even if my PS doesn't require it. I have several new 12V fans, and none of them will spin up when connected to either header. The issue is less an airflow one (I also have a rear chassis fan connected to a 4 pin PS connector, and it really sucks ;-) ) than it is that I'm afraid something is about to die completely. Things on a MB that are supposed to give 12V had better be giving 12V, I figure, or who knows what else could be messed up?
Would be suspicious that the ATX power connector wasn't fully seated or one of the connectors in there have partially backed out and moving the cable was enough to break the circuit. But the problem can be on the 0v. side also.
Ed Fair
Give the wrong symptoms, get the wrong solutions.
Ed Fair
Give the wrong symptoms, get the wrong solutions.
chriseubank
MIS
It's sorta weird that opening your case would yield the results that it does ..
Could it be that when the side case panel is attached, that it is moving some of the electrical wiring and causing an intermittant short?
Looking at the manual for your mobo, the centre pin of each of the connectors should be giving off +12 volts. The manual is Here
Could it be that when the side case panel is attached, that it is moving some of the electrical wiring and causing an intermittant short?
Looking at the manual for your mobo, the centre pin of each of the connectors should be giving off +12 volts. The manual is Here
- Thread starter
- #6
Ed,
I thought the same thing. Which is why I took it all apart and tried another PS, with an entire 'nother ATX connector. Same result. Unless maybe there's something funky with the ATX connector on the MB iteslf ... ? I was specifically looking at that area on the back side of the MB when I had it apart, before, after and during testing of the backup PS ... and I just didn't see anything out of the ordinary. Thanks, though. Any other ideas?
I thought the same thing. Which is why I took it all apart and tried another PS, with an entire 'nother ATX connector. Same result. Unless maybe there's something funky with the ATX connector on the MB iteslf ... ? I was specifically looking at that area on the back side of the MB when I had it apart, before, after and during testing of the backup PS ... and I just didn't see anything out of the ordinary. Thanks, though. Any other ideas?
- Thread starter
- #8
Update: I got out the meter, and what I found was kind of astonishing (to me, anyway, not really being an expert at this level of things). The 3-pin headers that won't spin a fan have the following voltages: ~3V, ~12V, Ground, just like they're supposed to, and just like the CPU fan header, which will spin any fan just fine. The difference between the one that works and the ones that don't, is that the one that works has some current! My meter isn't made for testing this, and I blew the fuse on it at first, so it has over 500mA. I replaced the fuse with some handy aluminum foil (just for a minute), confirmed that the "good" one pinned the meter, and the the other ones do not move it in any perceivable way. What does this mean???? Any ideas?
Broken trace, resistor in the circuit, or thermostat. Whatever is in series with the header has enough resistance that it drops the operating voltage. Your meter doesn't pull enough to cause a noticable drop.
Ed Fair
Give the wrong symptoms, get the wrong solutions.
Ed Fair
Give the wrong symptoms, get the wrong solutions.
- Thread starter
- #11
Yep, micker, I sure did. That was my last gasp before I started this thread. I really thought that might work, because I was on a BIOS rev that ASUS just doesn't like to talk about. I was on 1017, and there are no references to it on their site anywhere now. You can get 1016, and other archive ones, or the latest, which is 1018. 1017 is conspicuously absent, so there must have been something wrong with it. I flashed in 1018 and when that didn't help, I decided to ask for help. Anyway, I've given up. I think there is either some kind of firmware logic problem (not BIOS) related to sending current to these fan headers, or a short that I'm never going to find. So I just plugged that front chassis fan into a 4 pin PS connector and that's that. I'm expecting that I'll be in the market for a new MB sometime soon....
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