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Thread: Where to steal power?

  1. #1
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    Default Where to steal power?

    OK Mac hackers and electrical types.........

    One of the Xserves at work is under heavy load 24/7, and the PCI slot area is running too hot (in the warning range). Both slots are in use: one Fibre Channel, and one video.

    I was thinking I can dump the video and leave the slot open to hopefully push some air out the back. If that doesn't get the area cool enough, was thinking about a PCI slot fan. But.......where to steal power?

    Xserves don't have any standard 4 pin molex connectors, or any other spots (that I am aware of) where I can easily steal some power. Hot swap SATA drives in hard wired bays. They do have a bank of about 8 small fans that all run off a single plug, but I don't know if they are wired in series, what the voltage is, or anything else. Other than that, can't think of any other plugs or power available.

    I had hoped I could find a PCI slot powered fan (with no other power required), but after looking at the google, I don't see any.

    Thoughts? Safe hacks?
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  2. #2
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    Never been in an XServe. I would imagine it's pretty cramped in there though like most single rack space gear.

    Tying into the existing fan circuit is likely the easiest/safest way to go. I would bet that it's 12VDC, but you'd probably want to put a meter on it just to be sure. If the fans don't have the voltage/current draw listed on them sometimes a search on the model # will give you the specs.

    I have a 12V single PCI cooler in the slot next to my 4Ti since it's fan died. I have it undervolted to 7V to keep it quiet, but it still moves enough air to keep the GPU cool without it's own fan.

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    Matt,

    What about the optical drive? Is that SATA too, or is it PATA? Because if it's PATA....

    Edit: scratch that idea. I just saw a DIY for the optical drive, it's a slot loader. The manual doesn't even mention a separate power cable for that. Just a single orange plastic cable.

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    Which XServe? While checking out the optical drive, I came across another manual for DIY for the optical cable:

    http://manuals.info.apple.com/en/Xse...DriveCable.pdf

    In that mention there's mention of the "fan array" under an airflow duct. And in the 2008 Xserves, there's a connector for that. Gotta be 12 V (or 7 or 5V) suppling juice for those fans I would assume.

    Of course if it's an older one, then never mind...

  5. #5
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    It is the previous model, a G5. The optical drive setup is the same, so no easy help there.


    But very similar inside to the current model you linked to. Very similar fan array too..........comes out as one unit. Not that simple though, as each fan is linked to a different sensor and they all spin at different speeds based on temp. Still, seems like the only place to steal power from.

    Been pondering trying to ID the fan in the array that is designated for the PCI area (currently spinning at about 13,000 RPMs instead of the normal 5-6000 RPMs) and grab power from it, so that the PCI slot fan spins up and down with the correct. OTOH, since the PCI are and its fan will be hot/spinning fast all the time, and noise is no object in the colo facility, maybe spin it the added in PCI fan up to 100% speed all the time and not think about it again.

    Need to crack one open and review, maybe I am missing something. The PCI fan idea just came to me this morning while looking at options for the dead fan in my GF4Ti.

    Good thoughts........keep 'em coming.
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  6. #6
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    Was my thought too Eric

    Buy a Slot-Cooler
    1. drill a whole into the plate,
    2. cut the connector off the fan and put the cable thru the whole
    3. cut the 12V connector of the PSU use electrical clamp to put the cables together, done

    PSU
    http://www.powerstream.com/12v-index.htm

    FAN
    http://www.titan-cd.com/eng/system/004.htm

    Regards

    Nicolas
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  7. #7
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    Hi ya Nic,

    Say, I like that. Don't want to muck around too much in the Xserve. This is a prodcution box. My skills are OK.....but.....one slip, and I have a serious issue. Saving the hacks for the home boxes.

    So yeah, outside power solves that. Based on airflow and a known brand, I was leaning toward this fan. Already have 12V DC power supplies laying around at work. Do I need to consider amp ratings on the 12V supplies? Sad to say, I don't understand the relationship between Volts and Amps.

    As always, you are short and to the point.
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

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    THX Unc.

    Yes, the fan you picked has 0.2A so the supply should have at least 0.3A or 300mA or more.
    The supply form my link has 0.5A or 500mA.

    Most PSUs from external drives etc. do have around 2A.
    As long as the supply can deliver more power than the fan is needing its ok.

    Regards

    Nicolas
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  9. #9
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    Great. Sorry, missed that in your link.

    First things first: will pull the vid card and see what happens to temps. The G5 Xserves move air pretty well, but by the time it get back to the PCI area it is pre-heated pretty high and there is a big dead spot with both PCI slots filled. Pulling one card and leaving the slot open may let enough air move through the PCI area to solve the problem.

    If not, nice to have a workable plan B. Thanks fellas!
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

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    If the problem is a heat accumulation in the case a fan will do better than just a hole

    On my MDD it was the same thing by removing the pcislot covers temps stayed the same cuz the heat was trapped under the top of the case and couldn't get out.

    By installing a slotcooler the heat got exhausted, temp drop down.

    Regards

    Nicolas
    Custom Configurations! Rad Hacks and Mods!

  11. #11
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    Quote Originally Posted by Nicolas View Post
    If the problem is a heat accumulation in the case a fan will do better than just a hole
    No doubt!

    With the 1U case, and the straight through air flow - once one slot is empty - it will be interesting to see exactly what happens to temps. Will be a day or three before I can open up the slot to document the change.

    Here is the problem now:
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  12. #12
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    Default Usb?

    Hey Matt,

    Well I went looking for a slot powered slot fan. Didn't find any, but I stumbled across this Thermaltake USB powered fan. That's the Shack because it's gotta a decent photo , but there are other places that sell it.

    I'm not sure how you would/could mount it internally, since it doesn't look on it's own pre-fabricated for a slot. But it's basically a bare-fan with the USB & fan control stuff mounted on. So one thought could be to buy the Thermaltake for the electronics and see if you can slice in and rig it up to a genuine slot cooler.

    With the USB electronics, you get to steal USB power without any splicing in to the internals.

    Just a thought.

  13. #13
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    That looks interesting too. Yeah, I have already decided I will not steal power anywhere that involves splicing, so USB is an option too.

    Thanks!
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  14. #14
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    Sounds dumb but, have you cleaned out the Dust with a vacuumcleaner!

    Or, could it be that the PCI fan is kaputt?

    Because of the 13.500 RPM readout?
    Looks like the highest readout of a fan I ever saw and I can't believe this.
    The highest read of the PCI fan i ever saw was 7.000RPM.

    1. Its a readout error
    2. The readout is wrong
    3. Or the Probe/Sensor is defective

    If you can replace the Fan-Unit with a "known as good" one and see if there is a difference.

    See here:
    http://discussions.apple.com/thread....sageID=6652538

    Regards

    Nicolas
    Custom Configurations! Rad Hacks and Mods!

  15. #15
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    All good thoughts.....but I think it may actually be correct.

    This particular box is pegged at 100% CPU all the time (long story, but by design for the software it is running). The first time it jumped up above the warning level, I actually swapped out the entire Xserve with a second identical one. No real change; they both run write on the ragged edge in this roll, and both run fine under a normal load. That's what lead me to think that the dead spot where the PCI area is (where the temp problem is) is probably legitimate

    Most of the time the temp is just below the warning area, but the fan is always above the normal range which appear to be about 4000 - 8000RPM - to keep it from overheating. As and example, jere is a third G5 xserve that is a dual 2.3, runniing 10.5.2 Server, that is almost idle:
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

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    Forgot to mention that I also blew the dust out (never much on these babies as they move too much air for much to build up), swapped out the fan array (we have an Xserve repair kit for just this sort of issue), and it made no difference.

    Could be a bad sensor, or a software glitch I suppose, though I don't how I would fix either, even if I could prove it.

    Getting air moving in the PCI may be the best test.

    And yes, these fans scream in high speed mode.....so I think the RPMs are legit.
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  17. #17
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    Unc,

    I was just thinking out loud


    Yep, installing a slotfan seems to be the best you can do.

    Regards

    Nicolas
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  18. #18
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    Hey, I hear ya. Was my first thought too..........: almost 14,000 RPMs? That can't be right.

    I had the third (testing box) on the bench today when I grabbed those snaps, and with one card out, there was a pretty good amount of warm air flowing out, even with the PCI fan spinning at a relatively slow speed. So I think we are on the right track here: let the heat out of the dead spot, and better yet, help it along.
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

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    Just curious that the Xserver heats up that much with 2 cards installed

    Poor thermal design...


    Good that you saw it soon before something went south.

    Regards

    Nicolas
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  20. #20
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    Yeah.....hate to admit it but under heavy load, this appears to be a bad spot in the G5 Xserve design. The left rear corner doesn't let air out, and (guessing) the Fibre Channel card may add some heat.....so, trouble with a heavy load box. I think the high RPMs would prove that, even if it is able to stay out of the warning track. This box is in a colo facility that is something like 75 F, so imagine what we would see if it was in a room at the max temp Apple spec allows, which is 95 F?

    The good news is that the Current Xserves are a completely diffferent PCI layout, with them side by side in the middle, instead of stacked in one corner, so it looks like this issue was likely resolved. Better be with the Quad CPUs.

    Oh, and I was wrong.....there is a bank of 7 fans for everything else, but the PCI fan, while next to the rest, is actually wired separately. While I think I could steal power, I still feel better about your plan with an external PS. Kinda ugly, but safer to the box.

    Expect to pull one card tomorrow, will see what changes.
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

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