View Full Version : PCI versus PCI-X

08-17-2004, 09:23 AM

I just picked up a dual 2.5; I've installed a MotU (Mark of the Unicorn) PCI-424 FireWire audio card. The card is _not_ listed as PCI-X, but fits into a PCI-X slot. MotU recommends installing into the first available slot (slot 2, a 100-MHz slot).

I'm lucky in that I don't have any emergencies scheduled for this week for that machine, so I am not powering up anything until I'm sure I'm doing the right thing.

My questions are:

1.) Does the PCI-424 card not being PCI-X "mean" anything? Does the card _fitting_ into the slot mean that it's 3.3 volt?

2.) I saw Kaye's note posted earlier that the two 100 MHz slots (2 and 3) share a common bus, while slot 4 (133 MHz) is separate. Thus any other card installed in slot 2 will potentially run at the slower speed. I can handle this, but I'm wondering if it's better to install the card into slot 3 so that there's some space above the video card's heat sink. Does that make sense? Is there any feedback yet about heat issues in the PCI space? I got the beast with the small video card (heh, 128MB...my old SE-30 had an 80 MB _hard_drive_ ;-) , so I've got all three PCI slots available. I freely admit that I'm skittish about installing another card _right_above_ that ATI heat sink. Am I being too conservative? The machine is not going to be used for graphic-intensive applications, so I'm thinking the video card might not run too hot, but I am wondering if I fill in all three slots how hot things could get there.

BTW, I nabbed a bunch of RAM and a Hitachi 7K250 ('Gurus, of course) and I have to say that this was by far the easiest install I've ever done on any machine of any flavor.

3.) Given that I'm starting to fill this beast up, if I were to add either an LVD or SATA outboard RAID config, which would be the better slot for running the RAID.

4.) Along with cooling the room, is there any additional benefit to running a fan so that the air around the computer circulates more thoroughly?

As usual, thanks in advance!


08-17-2004, 10:51 AM

We have a couple of folks using MOTU 424 PCI cards. there are some caveats to full G5 compatibility, here's the support page from MOTU on it:

PCI-424/G5 Compatibility

Apple's Power Mac G5 computers deliver extreme speed increases that greatly enhance MOTU hardware and software. The G5's PCI architecture only accepts 3.3-volt PCI cards. As a result, first generation PCI-424 cards do not fit in the G5's PCI slots. MOTU has developed a 3.3-volt PCI-424 card that is fully compatible with G5 computers. In addition, an affordable trade-in program is now available - see below for complete details. We call this card the PCI-424/G5 card, and it works in all G5's, as well as all earlier PCI-424 compatible Power Macs (G4, G3, etc.)

First generation PCI-424 owners can trade in their card for a PCI-424/G5 card for $99, plus shipping and handling. If you purchased your PCI-424 core system on or after July 1, 2003, there is no charge for the PCI-424/G5 trade-in. Proof of purchase is required to waive the trade-in fee.

This program is available to registered owners of a PCI-424 core system: (2408mk3 core system, 24io core system or HD192 core system).

To place your PCI-424/G5 trade-in order, contact MOTU customer service in one of the following ways:

by phone at (617) 576-2760
by fax at (617) 576-3609
by email

International customers: please contact a MOTU distributor /dealer in your country.

Registered PCI-324 owners can upgrade to the PCI-424/G5 card for $295 plus shipping and handling.

Since your 424 fits it is a 3.3 volt card and should be fine. I called MOTU for an Australia based 424 customer and found that while the call center employee I got was less than a stellar example of knowledge he was helpful to the extreme. And in fact called me back to 'fix' an error on his part. He had to search the web for our phone number since all he knew was 'Rick from MacGurus' called and asked a bunch of technical stuff. I give him points for caring, points for getting it right and points for going the extra mile. All in all a very good experience.

I believe you can fire up and run that card with a clean conscience :)


08-17-2004, 11:04 AM
I just saw this on MacInTouch.com and wonder if it pertains to your situation:
10.3.5 System Freezes

Don Mac
As followup to my reader report dated Aug. 16, concerning the Kernel Protection Errors, I'd like to add the following:

As per suggestions that were posted to my thread at the Apple Forum, I started checking hardware items and peripherals. I found that the kernel errors were being caused by my M-Audio UNO MIDI Interface. Disconnecting it caused the Kernel Protection Errors to cease. I don't know what it was with the M-Audio device that cause the problems, since I use the latest drivers for it.

I have notified M-Audio through their Tech Support page about the 10.3.5 update apparently causing problems with this product.

Anyone else having a problem with their UNO MIDI Interface after updating to 10.3.5? Unless you have a Radeon 9800 or the new not yet released NVIDA card I wouldn't worry.

As to SATA card in the #3 slot, probably not. As for SCSI, if you can afford to, it is nice. SATA can save you $$$ and still give you 1-2TB of storage or 200MB+ of sustained I/O. I wish I could say that integration of SCSI, SATA(2) and "Serial Attached SCSI (SAS)" were ready and fully tested. the only thing that comes close is our HUGE MediaVault.

08-17-2004, 11:16 AM

Thanks for the replies! Yes, MotU is very helpful, but I figured I'd also check with the people I _really_ trust for Mac hardware issues! ;-)

Indeed, I did just get the thing through the trade-in, but subsequently got the willies when I started, arguably unnecessarily, thinking about the whole PCI vs. PCI-X issue.

On the LVD tip, do you all carry the ATTO stuff anymore? I've got a Miles2 in a souped-up 7600 that has served me _very_ well for the last (almost) 4 years, so I'd not be opposed to that option. If I could get sustained reads/writes in the 50 MB range, I'd be way happy (this beast is replacing an ol' beige Artemis machine with an IBM first-gen 10k big-as-a-house single-ended drive that also served me well, so if I can, in a reasonable way, beat the pants off the throughput of that drive, I'd be way happy).

I figure I'll start by just using the extra internal Hitachi and take it from there (of course, following the "backup, backup, backup" mantra).

So, is it correct to say that basically the upshot is, as regards PCI and PCI-X, that if the card fits, you can wear...er, use...it? Also, that it's best to use the slots in order, though one can skip a slot to put a PCI card in slot 4 just to get the bus separation?

Again, thanks for all the info!


Oh, btw and for whatever value, TZ, M-Audio is separate from MotU (M-Audio used to be called MIDI-Man [and was just purchased by Digidesign/Avid, makers of ProTools], MotU is "Mark of the Unicorn". I've always wondered what kind of marks unicorns leave, but I've been afraid to ask. ;-)

08-17-2004, 11:45 AM
It has been quiet on the ATTO front. As for "getting 50MB/sec and be happy" - well, nearly anything SATA or SCSI will punch through the ceiling and hit 55-70MB/sec today.

08-17-2004, 12:02 PM
Just so all can hear the deal on ATTO, we aren't yet in a position to carry them. ATTO sales are very attentive to us and make frequent calls, but the distribution policies of ATTO Technologies is to only sell to LARGE buyers. And now that they own the Mac SCSI market exclusively it will only get worse, at least until another competitor gets in the game.

Buying through the distribution chain is a real joy {dripping sarcasm}. Unfortunately we can at time buy retail cheaper than we can buy wholesale. That's because the largest distributors for ATTO also own most of the big retail houses. That means the wholesale distribution network competes with its dealer customers by selling out the backdoor as Buy.com, PCMall, PCNation and so on.

The weird part is that when you check prices there is a HUGE difference in the price of the same product, going out the same shipping dock, sold by the multitudes of various retailers all owned by the same company.

We are always looking for a source. We also refuse to sell at a price that basically doesn't take care of our customers needs. As soon as a source becomes available we will be in position to offer the product line though, and you'll all hear it from us.

BTW, in case anyone is interested, MacGurus is running a pretty good sale on Huge arrays. 10% off retail right now.


08-18-2004, 08:50 AM
Again, thanks for all the info!

One last question: if one were to (e.g., temporarily until getting an outboard LVD or SATA RAID rig) use just 2 cards, is there a benefit...or a caveat for that matter...of running one card in slot 2 and one in slot 4 to get the bus separation? In particular, if a card is "compatible" with the 100 MHz bus (i.e., compatible with the PCI-X slots in a plain-vanilla way), will it work in slot 4 and just not take advantage of the 133 MHz bus? Is there any general approach to loading the PCI slots?

08-18-2004, 09:42 AM

There is no perfect answer to where to install PCI cards. You need to analyze the cards and decide how they will play together.

Many PCI cards will run at a couple of different speeds, like the Firmtek SATA card or the Miles2, both are 66 MHz cards that will also run at 33 MHz. For best speed you should separate a 33 MHz card from a 66 MHz card since if you install a 33 in the 100 MHz slot, both 100 MHz slots will now be at 33. It might pay in that case to put a 33 in the single 133 MHz slot and leave both 100 MHz slots unaffected.

Some cards will only run at a given higher speed. In that case installing it in a 100 MHz slot with a slower card would make it non-operational.

There are too many PCI cards to cover them all. If and when you have a specific card set to manage we will all be happy to help you out and figure your best install solution. A few extra advisors never hurts (you can always ignore our advice if it looks like going it alone would be saner :)

In general, you can mix similar speed cards in the 100 MHz slot, keep any card that has a unique speed in the 133 slot.



08-19-2004, 12:49 PM

Thanks for the info! Here are the cards I'm thinking of using on the beast:

1.) MotU PCI-428 FireWire audio card

2.) TCElectronic PowerCore card (full length version)

3.) ultimately, a RAID/host card (either LVD or SATA)

I'm contacting MotU and TCElectronic to find out if their cards are 33 MHz or 66 MHz. If I start with the MotU and TCElectronic cards, would it make most sense to put them on two separate buses (i.e., the 100 MHz and 133 MHz buses)?

Thanks again!


08-19-2004, 01:07 PM
I think you are lucking out. All those cards are 66 MHz if I am not mistaken. They will play well together in whatever slots you use.


08-20-2004, 12:11 PM
One last question! ;-)

If I start out with the MotU and the TCElectronic cards, is there any benefit to putting one on the 100 MHz bus and the other on the 133 MHz bus?

Thanks again!

08-22-2004, 09:54 PM
Er, just to make clear my question...if the two buses (100 and 133 MHz) are separate, is there any advantage to putting one card on each bus to maximize throughput or am I effectively worrying about "gilding a lily"?

Thanks again!

08-22-2004, 11:39 PM
Those are both old slow cards, comparatively. Placing them in any slot is not going to make them faster since your PCI-X bus is substantially faster than needed for them. Only mismatching them with cards that are slower or cards that require a faster bus speed should matter.


08-23-2004, 01:57 PM
Thanks again for the info. I'm contacting both outfits to get the official line on specs and willl share when I get them.

I guess what I'm wondering, and this may just be a reflection of my ignorance, is that if the cards are both 66 MHz, then together (assuming they'd be running full-bore), they'd flood the 100 MHz bus (i.e., 2*66=132~133) and whether there'd be any advantage to putting them on separate buses to maximize throughput (I am hoping to really put them both to the test).

Do PCI cards typically or rarely get up to the full bandwidth they're rated at?

I guess I'm probably guilty of "living in the past", but I remember seeing the processor meter on my beige G3 (that this G5 is replacing) max'ed out when running lotsa tracks and just a _few_ audio-processing plug-ins...granted this G5 is way faster, has way more RAM and will have this PowerCore card onto which I should be able to offload a lot of this processing.

Thanks again!

08-23-2004, 02:40 PM
I've heard people are able to do real-time editing. PCI-X may need more work, but they do have 1GHz front side bus (vs 66 in Beige) along with true DDR memory (200 x 2) and AGP 8x.

Potential. As in "on paper." Ultra320 is a specification more than anything. SATA support for more than 65-70MB/sec. vs. potential maximum I/O thruput.

How well two cards share a bus. The SeriTek/1S2 should not be placed in shared bus and definitely not two in the pair of 100 MHz PCI slots.

The fact that a 33 MHz card will cause the bus to perform at 33 MHz also for the other slot is a downside. Why isn't there a single 33 MHz PCI bus maybe? one that might even support old style "universal" 3.3v along with 5v?

Is it as bad as the 6-slot with bus-master slot and two buses, repackaged? is the past that hard to shake off?

08-23-2004, 03:40 PM

DOn't worry about it. In this case 66 MHz is the clock speed and putting two 66 MHz cards means they both run at 66 MHz. YOu can't add clock speed together, just make sure they can run at the same speed.

Where you might have a problem is in bandwidth (with cards that needed more than the two you are planning to use). Two 64 bit cards that actually needed all the throughput of a PCI slot at 66 MHz/64 bit might just make a PCI bus have issues. Not in this case though. THose cards will run fine together in a lot slower PCI bus than a G5s. THe comparison to a G5 is like the difference between a 2 lane country road and a major freeway... no comparison at all. THose cards are not very high in need, so just determine if they will get along well together and put em on the 100 slots and let er rip.


08-24-2004, 09:37 AM
Rick and TZ,

Thank you for all this info...I did determine that the TCElectronic card will run at either 33 or 66 MHz and I'll just assume (unless I hear otherwise from MotU) that their card will run at 66 as well.

The people at TCElectronic responded (they're from Denmark, as regards English usage):

"the Powercore supports 66 Mhz and if you have the possibility to use it on a different PCI bus as you will have more bandwidth available on 2 busses, but it will work fine on the same bus too."

Here's an interesting blurb from Apple's site about all this:


"Power Mac G5: How to Improve PCI Card Performance

Learn how to take advantage of improved PCI card performance in Power Mac G5 or Power Mac G5 (June 2004) computers with PCI-X slots.

The architecture of the Power Mac G5 computer provides improved performance for PCI cards that transfer data (such as large video or graphic files) directly between cards.

To benefit from this performance, pair the cards in PCI slots 2 and 3. The slot numbers can be found on the left plastic card guide."

I'm wondering if the CueMix feature on the MotU PCI-424 could talk directly with the TCElectronic card, which would seem to take advantage of the direct communication...I'll have to ask them.

So I guess I'll just leave slot 4 open until I get an outboard RAID rig.

Thanks again for all the info!


08-31-2004, 11:00 PM
Hello all again,

So, the drama continues...

Got everything fired up including a Hitachi 7K250 and beaucoup extra RAM...everything appears very happy (the beast sure does put out some warmth from the fans in the back).

Well, I go and install the drivers (I figured I'd just check to make sure all runs and then partition, reformat and install everything), when I get a surprise...

...I check the PowerCore control panel and the thing says its running at 33MHz!

Again, I'm using a TCElectronic PowerCore PCI and a MotU PCI-424 card...does this mean that the PCI-424 card is running at 33MHz and "forcing" the PowerCore to do the same? The TCElectronic people said that the PowerCore was dual 33 and 66 and would auto-sense.

Well, my next question is...since I don't have an external RAID rig and thus I have slot 4 (the 133MHz slot) open, should I install the PowerCore in slot 4, keep slot 3 (or slot 2, depending what people say) open and see if I can get full (more) bandwidth out of the PowerCore? Does this even matter? I am planning on loading the thing pretty heavy, but I don't know if the throughput to the card would get anywhere near the PCI limits. I think this has been already touched on, but seeing the 33MHz in the control panel has made me wonder.

As usual, thanks in advance!


08-31-2004, 11:04 PM
BTW, any way to tell what the PCI-424 is running at? The MotU control panel does not reveal this nor could I figure it out from the System Profiler.

Thanks again!

09-01-2004, 10:28 PM
Well, just to finish the thought...

So I move the TCElectronic card from slot 3 to slot 4, leaving the PCI-424 in slot 2. As noted yesterday, when the PowerCore card was in slot 3, its control panel showed the PCI speed as 33 MHz...now that it's in slot 4, the control panel is showing a PCI speed of 66 MHz.

It would be nice if there was a 4 PCI slot G5 with 2 133's in it...

I saw this thread...what is "color-compatible"?


I'm likely going to be relying on the PowerCore card to do some heavy dsp lifting, so I'm thinkin' it's gonna stay in that 4th slot just to maximize the bandwidth. I guess this also establishes that the PCI-424 is a 33 MHz card (which is fine as it's really not doing any DSP track processing anywho...it's mainly an I/O card [and the CueMix feature talks directly to the breakout boxes {in my case a 24I/O and a legacy 2408}, so CueMix doesn't even hit the PCI bus]). I still don't know any way to get the PCI-424 to reveal what its speed is, I just inferred this from the change after moving the PowerCore.

Oh, one more q: 33 is an "even" divisor of 100 (multiple of 3), but 66 isn't...however 66 is an even divisor of 133 (multiple of 2)...is that possibly why the PowerCore is running at 66 on the 133 bus, but wouldn't on the 100?

I'll have to tell MotU and TCElectronic of my results. ;-)

TZ said that it likely wasn't a great idea to put a SATA (or LVD, if I recall correctly) card on a shared bus, so I'm wondering if I want to do any outboard disk stuff if that means that FireWire is the way to go now. Any thoughts? I'm probably just going to use the rig as is for the first projects and be careful about backing up.

Thank you for the input, I have felt better about messing with things after bouncing some ideas around!


09-01-2004, 11:41 PM
Interesting stuff. I would have to say that you can drop the 66 MHz card in the lower 100 MHz bus if you need to instal another 66 MHz card. 2 66's will run just fine down there and you can then isolate the 33 in the top slot. That way you can add a SATA host card or whatever and not slow it down.

Sounds like you confirmed that card is a 33 anyway.

I wonder if color compatible means that the PCI expansion bays can't run a graphics card? Other than that I have no idea.


09-02-2004, 10:29 PM

Cool! Once I get an idea of how this thing will behave under load, I'll try that angle of using the TC card and a SATA card on the 100 bus and toss the PCI-424 onto the 133.

Thanks for the input! Now it's time to just try to put this beast through its paces with the current set-up and see what happens!

Eh, ad astra per aspera?