Strange Boot-up issue

Hey guys.

I have a problem at start-up that started happening just a few minutes ago when I added an extra fan to the side plate of my case.

here's what happens: I press the power button, computer turns on and then after 2 or 3 seconds it shuts itself down, and after another second or 2 it turns itself back on again and boots up normally.

This DID NOT happen before buying the fan and DOES NOT happen if I unplug the fan. I've tried it.

I don't know if there's anything wrong with this issue... it just seems strange... could it be PSU issue? Well, it would be strange... I don't believe this fan could cripple my PSU... it must not be that power hungry, it's just one of those fans that plugs into those 3-pin thingys directly on the mobo.

For reference, here are my specs:

Intel E8400 @ stock

GF 8600GT (does not require aditional power, just what comes from the PCI-E bus)

Asus P5Q Pro

2x2GB Transcend RAM 800mhz

Deer (generic?) 480w PSU.... it came with my case.

Extra: Just one cheap exhaust fan at the back of my case and this new fan on the side of my case.

As you can see, I don't think my system is that power-hungry... especially since I don't overclock (yet).

I'm a bit worried though, as this started happening as soons as I added this new fan I bought today... I fear my PC could be under perfoming because of this strange ocurrence.

But could a simple low-power fan cause this?

11 answers Last reply
More about strange boot issue
  1. Sounds like you either have a short in the fan or the generic power supply is having issues. Never heard of Deer power supplies, but those are the obvious two factors that need checked then eliminated.
  2. Step 1 disconnect that fan (for the time being)
    Step 2 GET A NEW PSU!!!!!!!!!!!!!!!!!!!!!!

    recommend this one:
    $50 replace that POS power supply immediately, if not sooner!
  3. What happens if you unplug the back fan and plug in the new one there? (For testing only!!)
  4. Well, Deer is not unknown to me, I've had a couple of PSUs from them before and never had problems, that's why I decided to keep it in the first place.

    Well, the thing is... my computer seems fine... doesn't restart randomly or shut down... I haven't tried gaming or benchmarking (just tried SuperPI to see if the CPU was not underpowered... it did the 1M test in 14 seconds, which seems perfectly fine @ stock speeds)

    Could this simple fan be overloading my PSU? Seems odd... I don't know if it matters or not, but it's a plain fan, no LEDs or anything so... I don't really know.

    BTW, do you know the type of connector I described in the first post? It's a 3-pin "thingy" on the Mobo... it's NOT one of those 12V cables that run from the PSU.
  5. It could be a problem with the fan sensor. Can you disable the fan sensor on that fan connector?
  6. I don't think it has a sensor... it's a generic low-noise fan. It cost 5 bucks :)
  7. nightsilencer said:
    I don't think it has a sensor... it's a generic low-noise fan. It cost 5 bucks :)

    If it has 3 wires, it has a sensor...
  8. Also try it on another motherboard port if you have one free.
  9. R-sky was right. The fan has a sensor. it has 3 wires. I checked the port it was pluged into, and it says "CHA-FAN 2" which i suppose means CHASSIS-FAN nr1.

    Could this be the cause? Should I have it on port 1? (my back fan is connected to a 12V cable from the PSU, so it's not connected to the mobo, and it has no sensor).

    BTW, I just noticed that after my first boot, if I shut down the computer, and turn it on next, this issue doesn't happen, but it happens if I turn the PSU power off on the switch at its back.
  10. "R-sky was right. The fan has a sensor. it has 3 wires. I checked the port it was pluged into, and it says "CHA-FAN 2" which i suppose means CHASSIS-FAN nr1."

    I meant Nr 2 :P sorry
  11. I have seen hundreds of Deer power supplies over the years and have to say they have been a cause for concern. They Have caused some extremely erratic errors which have caused many unsual symptons and have led to many hours replacing the wrong part because of a faulty Deer PSU.

    We all now tend to suspect and change any PC we come across fitted with A Deer PSU with another PSU that shows anything that isnt due to and obvious problem.

    Also Deer PSU's are a hazard when they die. I couldn't count how many PC's have been destroyed by a Deer PSU when they give up, they always blow and take out the motherboard and HDD(s),CD/DVD's and floppy's and sometimes usb attached devices and Grphics cards. Strangley enough the only parts to normally survive when a Deer PSU goes is the CPU and RAM.

    They are not all bad, some are still working years later, but their failure rate and signs of extremely strange symptons are a worry.

    Obviously this is from my experience, but I am not ruling out the fact that high resistance from the new fan wouldn't just affect the PSU. It will affect the motherboard too and the associated electronics for the fan control so could easily give you the errors you are getting now.

    I have seen some strange causes from add on bits over the years even, and have had to diagnose many faults even down to (yes believe it or not) A PC speaker stopping a machine from booting (and i have seen this more than a few times)

    First thing and easist thing to do is change the fan, if it works, cool! but even then I would change to Deer PSU when you get some spare cash.

    sorry for the long post but hope this helps! :)
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