CD-RW in PIO mode

Discussion in 'Computer Information' started by mrT, Oct 28, 2003.

  1. mrT

    mrT Guest

    My AOpen 40x12x48x CD-RW has had bad transfer rates the whole time
    it's been in this PC. In my old machine, it read and burned fine. Now
    writing above 12x or so causes the buffer to empty every couple of
    seconds, leading to 50+ avoided underruns (BTW, does a CD riddled with
    'avoided' underruns have any loss in performance or anything, or does
    the 'avoiding' just involve extra write time?)

    Anyway, I just discovered now in Device Manager that the drive is
    running in PIO mode, and refuses to go to DMA (with 'DMA if available'
    selected). Something makes me doubt it's a PIO-only drive. This
    machine and the old one both run XP, with no special drivers for the

    Any ideas as to what could be causing this? If it matters, there is a
    DVD-ROM on the same channel, running in UDMA 2, and two HDDs on the
    primary channel running in UDMA 5.

    mrT, Oct 28, 2003
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  2. mrT

    Thor Guest

    Well, I see this quite often, and beyond trying chipset IDE drivers from the
    motherboard manufacturer, there really isn't much that helps, IMHO. It may
    very well be that the drive *is* PIO. I still see some that are. I also see
    some that are UDMA, yet will only run in PIO. And, drives that will run in
    UDMA but won't burn reliably unless it is in PIO. My new BenQ 4X DVD writer
    only runs in PIO mode in XP, whether it is alone, or slaved to my 52X CD
    writer (which runs in UDMA 2). But, that being said, PIO mode should be more
    than adequate for writing to the drive, unless your CPU is very slow, or
    very bogged down by other apps. PIO mode can transfer up to 16.7 MB/sec.,
    which is more than enough to sustain well above a 12X write speed. Not only
    that, but CD drives can't even push their sustained transfer rates beyond
    that in the first place, regardless of UDMA mode. The UDMA only benefits
    short burst transfers, which in a sustained read or write session is
    practically worthless. The "avoided" buffer underruns shouldn't cause a
    problem with write quality. That is the purpose of buffer underrun
    protection in the first place. It will, however extend the burn time,
    depending on how many times it must pause to allow the buffer time to catch

    Thor, Oct 28, 2003
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  3. mrT

    mrT Guest


    Well, I'm going to try moving the drive around, and I'll look for new
    mobo drivers etc... just checking it wasn't something that could be
    fixed with a click somewhere.
    mrT, Oct 29, 2003
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