G5 Missing inlet fan

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G5 Missing inlet fan

Hello all! I'm a long a time reader and first time poster so please, be gentle 🙂

I've been a 'Mac guy' for 12 years or so but just recently picked up a G5 1.8sp from eBay for a seemingly great deal. This was to replace my work-horse 867mhz quicksilver. Anyway..
I get the 'new' G5 all setup and the OS installed (10.4.11), everything seems to run great, no crashing or locking up at all but the fan noise is outrageous! Right at boot the lower rear fan winds up 12x to its maximum rpm and just stays that way.
I've checked the temps of the cpu and case and they are well within operating ranges (New England winter, semi-finished basement). I've also acquired and ran Apple's diagnostic CD to do a thermal calibration which it passed. It also passed all the other tests except when testing rear fan(1) which was "spinning to fast" and failed. I've reset the NVRAM, PRAM, checked the firmware version and anything I could think of or research. At this point I was thinking logic board, right?

I open the case to check things out and it seems that I'm missing the 'inlet fan' that should be sitting in front of the CPU housing! My question is this, would that missing component make the rear fan work harder somehow? I'll be ordering an assembly for it shortly regardless, but I also wanted to inquire if the dual fan assembly found in the dual processor models would fit/work in my 1.8 single processor case. They seem to be cheaper and more abundant.

Any insight would be greatly appreciated 🙂

G5 1.8sp, Mac OS X (10.4.11)

Posted on Feb 8, 2011 7:58 AM

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Answer 1

OVB

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15 points

Feb 8, 2011 8:38 AM in response to Validas

I can't say if the missing fan will cause the others to ramp up speed. What I can tell you is that used fans are available cheap on ebay. I bought a G5 2.0 DP last year that needed a couple fans and a couple other components. Don't think I paid more than $10 for the fans I needed.

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Answer 2

Validas Author

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Feb 12, 2011 8:11 AM in response to OVB

Right you were! I paid about $15 shipped for a single inlet fan from ebay. Unfortunately, I can't tell if it works or not because in my excitement that the problem was fixed, I failed to notice there isn't anywhere to insert or plug in the fan assembly.

I've looked through several YouTube videos and many tare-down images of the inside of this tower and I can't manage to find anything that resembles the inside of my G5. There aren't even any guides in the case where one would slide in. All I have are three small wires pinned up to the top of the compartment; looks like 2 very small plugs and a case thermostat sensor.

Were there any models produced that did not have the front (left of the cpu) fan assemblies?
Is my case actually running as 'normal' ?

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Answer 3

Feb 12, 2011 12:26 PM in response to Validas

Does your G5 have four or eight DIMM slots?

Eight slots is the earlier (2003) version, and the top of the fan assembly should slide through the cutout slot in the bottom of the PCI divider area just to the left of the CPU module. The fan connector will mate with the front inlet fan connector right above the top DIMM slot. I suspect it is the same situation on the later unit, but I don't have actual information at my fingertips.

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Answer 4

Validas Author

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Feb 13, 2011 10:21 AM in response to old comm guy

This tower has 4 RAM slots but, they are not in the common horizontal layout. The RAM chips in this machine run vertical (top to bottom/up & down) and they seem to be a lot closer to the cpu assembly than other photos and videos I've seen. If the fan fit in there somehow it would end up sitting literally on top the RAM.

I'm assuming I have some rare configuration? I recently plugged in the serial number into one of those websites and found it's a 'late 2004' model.

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Answer 5

BDAqua

Level 10

250,379 points

Feb 13, 2011 10:54 AM in response to Validas

More info on your model...

http://www.everymac.com/systems/apple/powermacg5/stats/powermac_g5_1.82.html

Here's a video showing RAM installation, which shows a Fan removal...

http://eshop.macsales.com/installvideos/powermacg5_memm/

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Answer 6

Feb 13, 2011 11:25 AM in response to BDAqua

BDAqua wrote:
More info on your model...

http://www.everymac.com/systems/apple/powermacg5/stats/powermac_g5_1.82.html

Here's a video showing RAM installation, which shows a Fan removal...

http://eshop.macsales.com/installvideos/powermacg5_memm/

This Apple memory replacement guide, http://manuals.info.apple.com/en_US/pmg5memory.pdf seems to be for the OP's machine, i.e., vertical DIMM slots. They don't mention having to remove a fan, and there sure doesn't seem to be one in the picture on page 4, certainly not like the one in most of the PM G5 machines. (Learn something new nearly every day.)

Though ... looking at the picture on page 5 of the linked document, it maybe appears that the fan is snug up against the front side of the processor module? Clearly this SP 1.8 GHz machine is an odd duck in the G5 tower world.

Message was edited by: old comm guy

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Answer 7

BDAqua

Level 10

250,379 points

Feb 13, 2011 12:53 PM in response to old comm guy

Great find! 🙂

Clearly this SP 1.8 GHz machine is an odd duck in the G5 tower world.

Indeed, as well as the Late 2004 1.8 SP being the only PowerMac9,1, makes you wonder if there was a PowerMac9,2 about the same time the G5 iMacs went from PowerMac8,1 to PowerMac8,2 ???

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Answer 8

Validas Author

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Feb 14, 2011 6:00 AM in response to old comm guy

{quote:title=old comm guy wrote:}

Though ... looking at the picture on page 5 of the linked document, it maybe appears that the fan is snug up against the front side of the processor module? Clearly this SP 1.8 GHz machine is an odd duck in the G5 tower world.{quote}

I checked out that pdf and the image on page 5 does seem to be the correct model of my tower. You can even see the three wires tied to the top of the bay above the RAM. I can not image there being a fan removed from there.

As I mentioned in a previous post, the diagnostics did not reveal any missing components. The only error indicated was that rear fan(1), the lower fan was spinning too fast.
The machine does run fine, no crashing, and the temps are super cool due to the increased air-flow so I'm going to mark this thread as solved. I suppose I'll just chalk the issue up to a bad logic board, deal with the noise and hope one day that lower fan burns itself out. I appreciate all the help though!

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Answer 9

Validas Author

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Feb 14, 2011 6:05 AM in response to Validas

Odd model machine 'late 2004' 1.8sp / vertical ram slots, not designed to have a pre-cpu fan.

Bad logic board presumably causing the lower rear fan(1) to spin "too fast" causing excessive noise. Only un-tested solution would be to replace the logic board, or possibly re-seat the CPU and perform another thermal recalibration.

Machine continues to run without crashing or other errors; will deal with the noise.

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