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Q:  I have stuttering audio when playing back files from my Older Mac with a PCI IDE Card

A:  *UPDATE* - Acard released an AV Optimize that has been reported to fix the stuttering audio problem with Acard (and Sonnet ATA/66 cards) in older Macs.
(from the 11/1/2001 www.xlr8yourmac.com news page)

If you have an older (pre-G3) Mac with Acard PCI IDE card with stuttering audio problems, try Acard's A/V Optimizer (direct download link is here). A reader with a 7500 and Acard ATA/66 card reported it solved his problems. Acard notes it lowers performance (as does Sonnet's ATA/100 card utility noted in past tests here).
The readme file with the download has information on using it. The Sonnet ATA/66 cards were made by Acard, but the readme says the utility is only for Acard models. (I'd suspect it would work with Sonnet Tempo ATA/66 and RAID cards, and one Sonnet Tempo ATA/66 card owner noted it worked).
Sonnet's ATA/100 card is made by Promise and comes with their own A/V utility.

(Original FAQ info on the issue follows)

IDE PCI Cards and Audio playback (stuttering/dropout problems) from connected drives in Pre-Beige G3 Macs has been a problem for years; ever since the first Mac PCI IDE controllers were released. PCI IDE cards in pre-Beige G3 (7300-9600, clones, etc.) Macs usually have stuttering audio (and audio in movies) when playing back from the PCI IDE card connected drive. (Playback from the onboard SCSI is fine usually. There is no real fix that I know of. This issue was noted in the first PCI IDE Mac card review in spring of 1999 (see the main www.xlr8yourmac.com IDE articles page).

Although some older Mac (pre-Beige G3) owners report no problems, most do. Even Promax originally noted the PCI IDE cards were only suitable for AV use with Beige G3 or later macs. (Macs with G3 CPUs or later from the factory.) No vendor I know has a solution for this issue.

In most every case, a 60x CPU based Mac (7300-9600, clones, etc.) will have the problem, and having a G3 or G4 CPU upgrade installed will not help based on my experience and those of many readers.

Some say they don't have the problem but all the tips suggested by some as fixes (like a small disk cache, changing slot order, etc.) have not been a universal fix - in fact when I posted these, not one reader that had the problem said it helped. [See the Link to Acard's AV Optimizer in the update above if you have an Acard, Sonnet Tempo ATA/66 card or Turbomax IDE card.)

As noted in the Audio section and PCI SCSI controller section of this FAQ (and since 1997 in many news posts), PCI SCSI card connected drives also suffered from this problem, but lowering the card clock speed was usually the fix (or disabling UltraSCSI mode). However there are no utilities for PCI IDE cards to allow this. There's one theory that the lower PCI/Memory performance in the "Kansas" or "Mach 5" systems (8600/250, 8600/300, 9600/300 and 9600/350s) may be less prone to the problem, but that's just a theory and I can't very that. Safest is to assume you will have the problem.

Searching the Drive Compatibility Database is a good thing to do before any drive purchase, but remember that even if someone there with a similar mac and PCI IDE card reported no problems, that is not an assurance you will not see the problem. There are many combinations of software/OS versions (including Quicktime, sound related extensions, the codec used, etc.), Video card/drivers, PCI IDE card firmware, disk drivers, RAM (interleaved or not), etc. to complicate matters. With CPU upgrades, that adds another variable such as bus speed, CPU/cache speeds and cache modes, etc.

For those reporting no problems, sometimes someone with what seems to be the identical setup can still have stuttering audio. It's safest to assume you will see the problem with a PCI IDE card in an older Mac. The IDE drives are still great for general storage, etc. but be aware with older Macs it's highly likely you will have audio stuttering/dropouts when playing back files from the drives connected to an IDE card.