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Thread: Difference between LC and LW Cheetahs

  1. #1
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    Is there a performance, reliability, or other difference between these two series of Cheetahs? I'd like to upgrade a Power Center Pro.

  2. #2
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    LW is Low Voltage Differential 68 pin; LC is Low Voltage differential 80 pin SCA.

    The type drive that you need for your PCP is UltraNarrow (ends with N). It will plug right in to your 50 pin cable and match your Adaptec 2930BU UltraNarrow host adapter card. See http://www.macgurus.com/shoppingcart...dseagates.html .

    To properly use an LW drive, you need a LVD SCSI card. It it very unwise to get sucked into buying a SCA drive. The were designed for hot-swapping on servers and will cause you all manner of problems. Low-lifes sell them to the unsuspecting.

  3. #3
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    Are you saying that the LC Cheetahs are the SCA units that it is "ČÍvery unwise to get sucked into buying?"

    If the LC is the SCA unit I'll avoid it and go for the LW units with the SCSI card.

  4. #4
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    Yes, and there are a bunch out there at very tempting prices.

  5. #5
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    Clyde:

    Let me say it again. Your PCP came from the factory with a UltraNarrow (Fast 20) SCSI card. That's what your stock IBM HD is running on. A Seagate drive with the model number ending in "N" matches that card; just plug it in.

    The LW drives are great but you need a matching U2W or faster card to use them properly. You can attach them to a narrow bus using a 68 to 50 pin adapter which is bad (see several other current threads). The drive will perform at less than half normal transfer rates if it works at all.

  6. #6
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    Louie, I may be learning more than I asked, but that's fine. However, the following is copied from the Guru's SCSI accelerator information.

    "For vintage 32-bit Power Macintosh, the MIles2 reigns supreme as the best option.
    With internal and external 68-pin wide connectors, all you need besides a Miles2 kit to upgrade to Ultra2 performance is a drive, and possibly some mounting hardware and four screws. That's it. (We're pleased to include the screws at no additional charge.) Sometimes simplicity really pays off, and we think that is certainly the case where Miles2 is concerned. It does LVD, and it does it right."

    However, the following is copied from the Guru's SCSI accelerator information. Is it reasonable to expect that a Miles 2, an LW Cheetah, and the appropriate cables, will significantly reduce the time needed to copy, save, & transfer large files on a PowerCenter Pro with an XLR8 G3 upgrade accelerator?

  7. #7
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    Delete first sentence of paragraph 3 in preceding post. Operator error.

  8. #8
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    All that is true. The kit costs $200. The kit plus Cheetah will give you transfer rates of 35-40 MB/sec.

    You already have a 20 MB/sec card which should give transfer rates in the teens with a narrow Barracuda.

    Having never tried it, it's possible that the Adaptec card and the Miles 2 card may not like each other on your one and only PCI bus. If that happens, the Adaptec card will have to go and your old drive will have to run off the 5 MB/sec built-in SCSI bus. You can't run the narrow drive on the Miles 2 without unspeakable losses.

    I just want you to be aware of all those factors before you make a decision.

    I can say all this to some people and they will go to Tijauna and buy a SCA drive and then want us to tell them how to make it work.

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