Musings on Low-end SATA Cards in PCI Power Macs

- 2006.11.06

While searching for answers to my SATA problem on the Web, I decided to take my questions to one of the Mac forums I frequent. Through the seams of learning about my lunacy, idiocy, and illiteracy for making this attempt to jury rig an OWC 2+2 SATA PCI card to a clearly incompatible Power Mac 7600, I was able to glean useful information of great relevance to my experiment.

These suggestions, possible caveats, and other miscellaneous information can be distilled into a simple list, with my thoughts annotated following each point.

1. Mixing PCI v2.1 slots and PCI v2.2 cards can be dangerous because of the different voltage involved - 5v versus 3.3v.

I'm no expert (quite obviously), yet my research leads the following findings:

On face value, the OWC card is 32-bit, 33/66 MHz PCI/PCI-X, and the Sonnet SATA Tempo (which lists Power Mac 7600 compatibility) is also listed as 32-bit, 33/66 MHz PCI and Compliant 32-bit PCI bus version 2.2.

More research led me to the following tidbits on PCI v2.1 among various other PCI specifications

The PCI bus specification 2.1 calls for expandability to 64 bits and 66 MHz speed; if implemented this would quadruple bandwidth over the current design. In practice the 64-bit PCI bus has yet to be implemented on the PC (it does exist in non-PC platforms such as Digital Equipment's Alpha and is also found now on servers) and the speed is currently limited to 33 MHz in most PC designs, most likely for compatibility reasons. (Codepedia)

and

PCI Technical information

PCI is basically a 5 volt, 33 MHz, 32-bit bus with a basic data transfer rate of 133 Mb/s.

PCI also has many design options which can be combined in any permutation.:

• 64-bit bus extension - basic data transfer rate of 266 Mb/s
• 66-MHz extension - doubles basic data transfer rate.
• 3.3v operation - via a different physical connector.
• "MiniPCI" connector for laptops and PDA's (Codepedia)

Both the OWC card I tested and the 7600-compatible Sonnet Tempo SATA have this PCI card tab layout. Notice the first slot illustrated. My 7600's PCI slots correspond to this layout and, as noted, should be physically compatible.

Having the system recognize the card or connected drives is another matter. My utterly unqualified advice is that a user would not physically damage their older Mac or other personal computer by the simple act of installing a card into any appropriately shaped PCI slots.

2. PCI v2.1 and v2.2 may be subtly different in some other way than voltage support and tab connector. Additionally, the actual chips on the card are not reliably compatible with something related to the design of Old World Macs.

I can buy this point, as it seems to make sense. This point was distilled from the words of wisdom obtained from Larry O'Connor, CEO and founder of Other World Computing (OWC). I trust this fellow. He and his team were kind enough to offer troubleshooting tips even though I made it clear I was testing an unsupported setup. Class act all around, and I thank OWC for taking the time to talk with me about this issue.

3. Why mess around with such an old Mac? There are plenty of newer Macs to be had if you do a little hunting.

There's not much to say on this one, as the point is generally valid.

However, why not explain my viewpoint on this issue? At first glance it would seem silly to put such effort and money into Macs that aren't worth the cost of the SATA card itself, let alone the card, cables, and drives.

Easy answer: The money isn't going into these older Macs to keep them up to date - that's plain silly in most cases. Instead, think outside the box. I needed another hard drive for backup, and if not for the Power Mac 7600 I would have purchased an external case for about the same amount of money anyway. The hard drive cost was the same whether I purchased the SATA card or an external case.

If you find a SATA controller card that is compatible with older Power Macs like my 7600 (the Sonnet Tempo SATA is listed as one such device, although it costs more than the OWC competition and only offers internal ports), then why not.

When I acquired my 7600 it already possessed a G3 upgrade, a decent amount of RAM, built-in ethernet, and a handy audio/video personality card. With a couple large drives, I have a backup storage box and audio server all in one package. Not to mention that the 7600 isn't rotting in the landfill and still makes for a decent Mac OS 9 workstation if my main Mac, a 6-year-old iMac G3 DV SE, were to succumb to hardware component failure.

While I can't unequivocally give the OWC SATA 2+2 PCI controller a passing grade in this specific (and very much unsupported) configuration, it is a nice card. If you have the appropriate system, I'm sure the card works as advertised.

I can attest that preformatted HFS or HFS+ drives are recognized by the system and can be erased via the Finder's "Erase Disk" command. Throughout my testing, I haven't noticed any ill effect from having my 30 GB PATA drive acting as a Mac OS 9.1 boot drive in my Power Mac 7600. I'm guessing any adapted PATA or SATA drive would likewise function if first formatted in another computer and then installed into one of these legacy PCI Macs.

Bottom Line

For those with supported Macs, the US$50 OWC SATA card is very competitively priced, especially at the open box discount I was lucky enough to stumble upon, and this card is flexible in it's acceptance of two external drives, two internal drives, or one internal drive and one external drive. All you have to do is toggle the switch for each of the SATA channels to internal or external configuration.

The other card of interest is the US$80 Sonnet SATA Tempo PCI card, which gives a PCI or PCI-X equipped Mac two internal SATA ports. (I have not tested this card.) While more expensive than the competition, Sonnet guarantees compatibility with a far larger range of Macs - essentially any PCI/PCI-X equipped Mac or Mac clone.

There are other brands of internal 2-port SATA cards available, but they all list the same compatibility requirements for about the same price as the OWC 2+2 SATA. The OWC card looks to be a steal in comparison, and having the option of external or internal ports is quite nice, but the Sonnet card has been more extensively tested by Sonnet to work with a larger range of Macs.

It's a toss up depending on your needs and willingness to experiment. Either way, adding modern SATA drives makes for an easier transition when upgrading to a modern personal computer. The SATA connection is the way all new Macs are equipped for internal storage.

"Future proofing" oneself from the changing climate of modern computing isn't easy - maybe not even possible - but this simple upgrade makes things slightly more palatable when it comes time to migrate storage.

Breaking Information

Late Sunday night I successfully formatted my 320 GB Seagate SATA drive while it was connected to the OWC SATA card in my Power Mac 7600. More information will follow as I run more tests. Thank you for your patience, as this occurrence has allowed for the possibility of my viewpoint changing on this OWC SATA card.

I haven't collected enough data yet to know if my slight reservations can be erased, although there is a better chance that the card may receive a clean bill of health for operation with unsupported Macs, such as my Power Mac 7600. 

Links

• Old Power Macs and SATA Not a Marriage Made in Heaven, 2006.11.06
• SATA and PCI Power Macs: No OS X Joy, but You Can Boot OS 9, 2006.11.17
• OWC 2+2 SATA PCI
• Sonnet SATA Tempo PCI
• All about PCI Local Bus, Codepedia
• FAQ: Overview to different PCI cards and slot types and ways to combine them (kb2471), SWYX