Firewire powering exhaust fans?

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coius's picture
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Firewire powering exhaust fans?

I have a (heavily) upgraded Blue & White G4 System and I have noticed something I have NEVER seen before.
Ok, so I am going to plug something in to the machine. And I hear this "Whoosh!"'ing sound come from it. Mind you, I have no power plug hooked into it, nothing except for the FireWire cable coming from my iBook that is in FWTDM. I can't figure out what's going on, until I open it, and I see the exhaust fan above the PCI Cards running. I am trying to figure this out, since this is a 12v Fan, connected DIRECTLY to the PSU, and there is NO A/C plug connected, and nothing else except the FireWire cable coming into the case.

How can this be possible?

I have the Cable connected to a FW400/USB2.0 Belkin PCI Card in the slot closest to the hard drive area. How is it possible that this thing is going through my Motherboard, into the PSU and powering the fan? This is not the fan in the PSU, but the 7" Fan that sits about the Expansion slots

Is something wrong with this machine, or is this thing actually SUPPOSED to power this?

I have no other anomalies, other than this. And tbh, it freaks me out. And should I be worried?

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Joined: Jan 19 2005 - 23:30
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i wonder if its somehow back

i wonder if its somehow back feeding through your pci card back to the PS and they just happen to share the same 12v rail.. thats kinda funny though.

coius's picture
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yeah

At first it startled me. I thought it had some "Mysterious" Feed into. Then it turned into "OMG, Do the capacitors in that PSU actually have the power to keep running the fan?!?!" Then I thought "I wonder..." then pulled the FireWire cable. Then it stopped, but it scares me that if that FireWire port, which is only connected to a PCI slot through a card, if the PSU goes bad, and surges, could it kill the machine/drive on the other end of that cable?
That scares me, as sometimes we get small surges on the line, and I don't know if apple put a built-in auto-voltage leveling in their Power supplies. So I might be more wary of putting a Laptop on the end of that during small thunderstorms (I know, I'm bad about using computers during a thunderstorm, but I try to go onto my laptop wirelessly during that time. but it can be inevitable.)

We have a whole House Surge-protector put on our power box outside, and pay for it through our Power Companie's plan. I think it's like $15/mo iirc, it's not bad, especially since we are like 2nd to the lowest cost for power anywhere in the USA (we don't let monopolies run here in the midwest, and have our fair share of powerstations in the central USA to pull from) So I don't worry TOO much about it, although the thing has popped 3x already

Well, i probably shouldn't worry about it too much, but I tried it on the internal FireWire, and it looks like it runs on the internal PCI Bus as well, since it also powered the fan. It's just kinda odd...

TheUltimateMacUser's picture
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FW

If i plug a FW HD into my G4 tower, which is turned off, then run a FW cable from my tower to my ;book, i can see the FW HD on my 'book. So, what you're seeing is normal, i'd think.

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Thread name changed

The thread name has been changed to "Firewire powering exhaust fans?" to be more descriptive.

b. Please use descriptive subjects when you start a new thread. "Look at this!" is not descriptive.

-BDub

coius's picture
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sounds good

I guess I need to take a forum-writing class Blum 3 Sorry

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