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Fans wont stop - Mobo or PSU?

2K views 11 replies 3 participants last post by  Tyree 
#1 ·
Starting a few months ago, when I would shut down Windows, the case fans plus CPU and GPU fans would continue running (at a lower speed, since it's much quieter than when the machine is running) for a few minutes after everything else. There did not seem to be any power going to the hard drives or the optical drive. During this time, the power button on the machine would have no effect, even if held down for 10+ seconds. Over time, the length of time the fans stayed on got longer, staying on for approximately 24 hours at one point. Then, the problem just stopped one day.

I just recently moved, and when I hooked up my machine and plugged in the power, all the fans came on, and I am unable to actually power up the computer. It has now been in this state for going on 92 hours. All the case fans, plus the CPU fan and the fan on my video card, are running (again at a lower speed). Again, there does not appear to be any power to the hard drives or the optical drive. I have some cold cathode tubes hooked into the system, and they will come on if I hit their switch, but they are somewhat dim compared to when the system is running.

Oh, one last note, I am using a TTGI 520SS Quad Fan PSU. On the back of that unit, it has a switch for setting the PSU fans to Auto, Low or High. With the switch in the Auto or Low positions, the fans on the PSU are not running. If I set it to High, the PSU fans kick in.

I'm assuming that this would be either an issue with the motherboard or the PSU. However, I can only afford to replace one of those components in the forseeable future. My question is, which is more likely to be the failing piece of hardware? Is there a way to find out for sure at little or no cost?
 
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#2 ·
Well the problem might not be fixed untill you replace both but we need to know the specs of the pc before we can help further. If you can post the make and model of the following it will help us better.
Oem pc make and model (if the pc is made by dell, gateway, hp, ect)
Custom built
CPU
Motherboard
video card
ram
PSU (make, model, and wattage) found on a sticker on the psu
Drives

my prime suspect is the psu and if it is than it might have damaged the motherboard too, we won't know untill we know more about your pc.
 
#3 ·
It's a self-built PC.

CPU: Intel Core 2 Duo E8190
Motherboard: GIGABYTE GA-P35-S3G LGA 775 Intel P35 ATX
Video Card: Palit GeForce GTS 250 E-Green 1GB Video card
RAM: 2 x Patriot PEP22G6400EL DDR2 2GB sticks
Power Supply: TTGI 520SS 520W Quad Fan Power Supply
Drives: 3 x SATA HD & 1 x LG WH10LS30 Super Multi Blue Blu-ray Burner (I don't have the brand/model info on the hard drives on hand at the moment, and I'm not at home to pull the drives to find out).

Also, if it helps, I have 4 80mm case fans (3 in, 1 out) and 1 60mm case fan (out).
 
#6 ·
So, I purchased a new power supply, an Eagle ET-PSVTC550E-BK. I replaced the old PSU with the new one, hit the power switch aaannnddd...the fans come on for the briefest moment, then go off. Then they come on 4-5 seconds later, again for a brief moment (brief as in less than half a second), and go off...and on again 4-5 seconds later, then off, etc. :(
 
#7 ·
I unplugged everything, pulled the mobo out, reseated it, connected just the main ATX & ATX 12V power to the mobo, and the same issue occurs when pressing the power button. Fans on for less than a second, then off, then back on a few seconds later, repeating.

I would assume at this point that it's the mobo that's a problem.
 
#8 ·
I wouldn't write off the PSU as being the problem. The one you purchased is very poor quality. The price would be a good indication of the low quality.
Test the Mobo by removing all RAM and then power it up. You should hear a repeated single beep from the Mobo speaker. That generally means the Mobo is OK.
You can also check manually the Mobo for swollen or leaking CAPs and burned spots.
 
#9 ·
This is likely relevant, in one of the iterations of plugging and unplugging things, I inadvertently left both 12V rails unplugged. When I hit the power switch, the system powers up (I at least have power to the BR drive, as I am able to open the drive with the button on front), but I get no video. Holding the power switch down for 10 seconds powered the system down...until I released the button, then it kicked back on. As an experiment, I plugged in the 12V rail that's part of the "main" ATX plug, but left the one up by the CPU unplugged. Hitting the power switch powers up the system, but again I get no video. However, if I have the 12V rail plugged in up by the CPU, regardless of the connection status of the other rail, I get the momentary fan on, then off cycle going again.

Removed the RAM and started up, no beeps. Unplugged and replugged mobo speaker; still no beeps on start without RAM. Did physical inspection, saw no signs of swollen or leaking capacitors.
 
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