Increasing speed on FireWire 800

Discussion in 'Mac Pro' started by lloyd709, Jan 17, 2008.

  1. lloyd709 macrumors 6502

    Jan 10, 2008
    Barefeats has just said on his website that the FireWire 800 is much faster on the new MP due to the fact that it is 'now on the PCI Express bus':

    Would anyone know if this means that if I buy a FireWire 800 PCI Express card I would get these speeds?
  2. Toups macrumors regular

    Nov 23, 2007
    Are you installing into a new MacPro or an 07 Mac Pro? If an 08, you do not need the additional card :)
  3. newtech macrumors 6502

    Jun 2, 2007
    That is a load of dingo's kidneys. FW in the G5 and MP are integral to the K2 or ESB2 I/O controller chips and never pass through PCI-e.

    Now if you talk ADD ON FW, then yes a 1X PCI-e card will run circles around a PCI-x based FW card.
  4. lloyd709 thread starter macrumors 6502

    Jan 10, 2008
    Not heard that one before 'dingo's kidneys' - I'll have to remember that!

    But to answer the first post first, I've got a pre 2008 Mac Pro and I just want faster fire wire if possible.

    I'm not installing anything yet, I just read about the test on Barefeats.

    I'm not very technical that's why I've posted this question. Can you explain what part of it is 'dingo's kidneys' - the bit about what Barefeats said or the question I've raised?
  5. newtech macrumors 6502

    Jun 2, 2007
    In the PM G5 and all Mac Pro models the built in FW800 is part of the chipset and never has anything to do with the PCI-e bus or slots. Barefeats claims only make sense when comparing PCI-x add on cards to PCI-e add on cards, and even then the last G5's and all Mac Pro have PCI-e slots so claiming this is new in the latest Mac Pro's is wrong.

    "... maybe a dingo ate their baby ..."
  6. lloyd709 thread starter macrumors 6502

    Jan 10, 2008
    Sorry, I might not have been clear. Barefeats haven't said anything about cards, PCIx or PCIe. They made the comparison - as I understand it - between the FireWire ports already in the new MP against those in the old MP.

    I'm the one that brought up PCIx cards. Wondering if I could put a PCI Express FireWire card (if one exists) to get higher speeds.
  7. Firefly2002 macrumors 65816

    Jan 9, 2008
    Well, assuming your drive is being bottlenecked by PC800 speed overhead (possibly... I don't know what kind of bandwidth overhead there is on your FW800 port), then.... maybe.

    Both PCI-E and PCI-X have more than enough bandwidth to spare for a FW800 card. Hell, the 32-bit/33 MHz PCI slots on this Beige have enough bandwidth... FW800 has a max theoretical bandwidth of 100MB/s.. PCI 2.1 has 133 MB/s, PCI-X has, I think, 533 MB/s at the very least (some versions faster), and PCI-E... not sure. I think maybe 2.1 GB/s. Either way, if it's a bottleneck, it's a bug, not a property of the bus interface.

    What kind of speeds are you getting via your FireWire800? What hard drive are you running off of it?

    Lol. Be glad you're not running USB 2. What a crappy interface.. the overhead? About 50%. A good USb 2 connection will net you about 35MBps. A very good one. Most are 30MBps. Sucks =/
  8. lloyd709 thread starter macrumors 6502

    Jan 10, 2008
    I think I'm getting about 45 MB/s which I think is standard actual transfer rates for 'set in' firewire ports on the Mac Pro's ('old' ones anyway).
  9. cw2k7 macrumors member

    Jan 18, 2008
    In the old Mac Pro all 4 firewire ports (2x800Mbps and 2x400Mbps) are connected to a single 33MHz PCI bus which only provides around half the required bandwidth for supporting that number of firewire ports.

    In the new Mac Pro all the firewire ports are connected to a single PCIe 1x bus which provides double the bandwidth of the PCI bus (still not quite enough for all ports running at full bandwidth but much better than the old one)
  10. newtech macrumors 6502

    Jun 2, 2007
    Ok, even allowing that I was mistaken about the built-in PHY not being on a PCI bus, all the ports share one Firewire bus so realistically no more speed. If there were four firewire buses then yes there would be improved bandwidth.

Share This Page