power options - additional internal hdd

Discussion in 'Mac Pro' started by rtrt, Sep 25, 2008.

  1. rtrt, Sep 25, 2008
    Last edited: Aug 13, 2011
  2. grue macrumors 65816

    Joined:
    Nov 14, 2003
    Location:
    Somewhere.
    #2
    I'm slightly confused, are you wanting to power internal HDDs in addition to the four pre-wired SATA bays?
     
  3. rtrt, Sep 25, 2008
    Last edited: Aug 13, 2011

    rtrt thread starter macrumors 6502a

    Joined:
    Jan 19, 2008
  4. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #4
    Using the available molex connector from the empty optical bay is the simplest and easiest solution. :) If you still need another connection at that location, just use a splitter/Y adapter.

    If you can get the power connector off the backplane connector, you may be able to use a Y adapter/splitter with the correct molex/SATA connectors. Otherwise, you could hack the power connection itself if you have the skills and inclination to do so. ;)

    The PCIe connector on the logic board wouldn't be an option. I've never seen the cabling. What does exist would have male and female connections reversed of what you need. :eek:

    Why do you not to want to use the 4 pin molex connector available? :confused:
     
  5. rtrt, Sep 25, 2008
    Last edited: Aug 13, 2011

    rtrt thread starter macrumors 6502a

    Joined:
    Jan 19, 2008
  6. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #6
    OK. You have and need both DVD drives.
    Not certain on HDD's though.
    How many do you have installed internally now?
    How many do you plan to add?
    I can find you power somewhere I should think. :p
    Just not sure of the exact configuration. Answers to this may help immensely.
    There may be another way. Perhaps the only one, as I'm not sure how you plan to mount additional drives with all four drive bays occupied as well as both optical bays. The Mac Pro is woefully inadequate in available drive bays. :(

    It seems the answer may lie with an external enclosure. The number of drives would help dictate the size.
    Are you looking for them to act individually, or in a RAID configuration?
    One way would be to use an eSATA card, and eSATA enclosures. Depending on the card and number of drives, a PM (port multiplier) enclosure may be required.

    RAID opens up other possibilities. MultiLane, MiniSAS for example.

    I can certainly understand this.
    Yes. :)
    Look at the connections backwards. The PCIe cable attaches to the logic board (motherboard). The other end is a female 4 pin Molex connector. So to make this a possibility, you need a male 4 pin Molex to male 4 pin Molex cable. This would then allow you to power an HDD. Now I assume it will require a SATA power connector, you then need a 4 pin Molex to SATA power cable to finally connect to the drive. :D

    The PCIe cable and the Molex to SATA power cables are easy to find. Not so sure on the male to male 4 pin Molex. Didn't see one on span.com. :(

    There is a solution though. ;) The 4 pin male to male cable could be substituted with a power splitter (molex). Just not as elegant as the male to male only. :eek:

    Does this make sense to you?

    BTW, I know span.com can provide the cabling. Not sure where else. Maybe eBay UK?
     
  7. rtrt, Sep 26, 2008
    Last edited: Aug 13, 2011

    rtrt thread starter macrumors 6502a

    Joined:
    Jan 19, 2008
  8. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #8
    This is going to be incredibly difficult in the Mac Pro, and not advised. Not only the physical space issue, but the related thermal problems. The Mac Pro doesn't have the best thermal design I've seen. Not by a long shot. :(

    In my delusions, I was hoping to attach an additional drive directly beneath the drive mounted in each sled.

    Another investigation led me to a 4-2.5" internal drive bay. Fits in a single 5.25". It could work, if you are willing to mod the front of the case. There goes the warranty...:rolleyes: No purely internal version of this (no case mods required).

    One last possibility, and I think doable, is to buy a proper full tower case, and perform a Mac Pro transplant. If you, or I attempt such a thing, it might be a good idea to use a larger power supply, as they tend to have nice long cables. Otherwise, the current supply cabling would likely have to be modded for length. Again, the warranty thing...:eek:

    The only other solution I know of, and actually works, requires the use of the optical bays. Out of the question in your set-up.
    If you do this, your Mac Pro will almost certainly run blazingly hot. It will not only add any heat generated by the drives themselves, but restrict what air movement is currently possible.

    This and the physical space available in the Mac Pro aren't up to par for a workstation IMO. I'm in the same boat. 4 drive sleds is a joke for this class of machine.
    For all practical intent, there really won't be a choice in this matter I'm afraid. I would have mentioned this sooner, but didn't realize the quantity of drives you need.

    There are a few threads on enclosures, but I don't mind trying to help you locate a suitable box that won't break the bank. ;)

    What exactly do you need to do with these? RAID or individual drives (JBOD)?
    The cables you linked won't work. Wrong genders. Other reason as well, so keep reading. :eek:
    I was thinking they about the supplied voltages from the PCI-X standard, which has a +3.3, +5.0, and +12.0 V supply.

    You are correct, as the PCIe only uses the +3.3 and +12.0 V, and this would be the same on the additional power connector, as it makes no sense to provide a voltage that isn't used. :(

    Sorry about the confusion here. :eek:
     
  9. rtrt, Sep 26, 2008
    Last edited: Aug 13, 2011

    rtrt thread starter macrumors 6502a

    Joined:
    Jan 19, 2008
  10. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #10
    I've looked at these before. They look good, and may do the job quite well. My issue was that slot 4 needed to be retained for use, as the noiseblockers would almost certainly prevent the use of it. If it isn't an issue, it may well be worth the effort. I should have mentioned them, but had forgotten ATM. Sorry. :eek:

    Other members have looked to these as a possible solution, but I don't know if anyone has actually tried them in a Mac Pro.
    Quite useful program. ;) I can't imagine this not working, albeit a bit noisy. :eek:
    It would depend on
    1. What the connector is able to provide in terms of current.
    2. Number of devices (existing power draw) that is on this particular rail.

    That said, I would think it shouldn't be a problem, as the two optical drives would likely be the only devices attached. I'm estimating 12V@20A which is common to a 1kW PSU or so. Thus a total of 8 drives would be possible.
    Optical drives are about the same draw as an HDD. Avg use is ~25W, so add 10W for startup. (I usually try to figure power based on startup, not idle/avg draw).
    Adding 4 HDD's shouldn't be a problem in the slightest. This is assuming there isn't any other devices attached to this rail.
    IIRC, it does on the 4 drive bays. The ODD ports, I don't really know.
    Use these:
    Molex splitter (x1)
    SATA power (x2)

    These cables would allow you to run 4 drives. :D

    Found the noiseblockers for $9.99GBP /set
    So the whole thing would be $49.09GBP (VAT included), but no S/H. No idea how this would be to you, but would expect any external box to be more. ;)
     
  11. rtrt, Sep 26, 2008
    Last edited: Aug 13, 2011

    rtrt thread starter macrumors 6502a

    Joined:
    Jan 19, 2008
  12. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #12
    No fuses in PSU's that I've seen.

    It can take it for a very brief period of time (millisecond range). Decent ones do have some protection built in. But you shouldn't rely on this.

    When a PSU is overdrawn, it gets incredibly hot. So hot in fact they can glow cherry red. At some point the voltage regs go out, creating a direct short. Total melt-down, and they have a very nasty habit of taking stuff with it. Mem, motherboards, and CPUs in particular. :eek:

    In the case of a massive current draw, the circuit breaker in the panel will trip. It's when they draw too much current for the PSU, but not the breaker that the danger zone exists.

    Watch the temps like a hawk. Also, if it's drawing too much current, you would likely see some obvious aberrant behavior.
     
  13. rtrt, Sep 26, 2008
    Last edited: Aug 13, 2011

    rtrt thread starter macrumors 6502a

    Joined:
    Jan 19, 2008
  14. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #14
    :cool:
    Looking forward to seeing how it goes. Particular the X Swing. :D
    Maybe the upcoming Mac Pro will eliminate the slot issue for me. ;)
     
  15. rtrt, Jan 6, 2009
    Last edited: Aug 13, 2011

    rtrt thread starter macrumors 6502a

    Joined:
    Jan 19, 2008

Share This Page