JWL, thanks for confirming the 5000X - then it's clear ... this is from the documentation of a board with a 5000P
http://vsl.co.at/upload/users/449/dualchanneldualbranchmemory.png">
i don't think the difference between 2.66 and 3.0 will be significant, even noticeable - but there are always configurations needing each single quantum of CPU power(eg. altiverb)

the quadcores are at 2.66 currently (producing a lot of heat) - maybe apple waits for the quadcore low voltage processors reaching 3 GHz or more ... to make an argument why purchasing a dual quad looking better
christian

CM --

OK, now I need clarification! [:)]

If you glance up higher in this thread, you'll see the specs for my machine.

1. My understanding it that the RAM limit is 16 GB for the dual 3.0 xeon Mac pro. Does the 32 GB possibility mentioned in your last post exist for my machine, or is that a later generation of Mac Pro?

2. After doing some research, I and the person who helped me acquire the Mac concluded that I was OK leaving my pair of 512k chips in my computer, as long as we got everything in the recommended slot order. Is that info incorrect? Should I take 'em out, leaving just the two 4 GB chips?

I'm not an expert in this area, as you can tell!

Thanks,
PL

ad 1) at least the 5000P _supports_ 16 slots (grouped in 2 branches each 2 channels each 2 banks), this doesn't say the board _has_ 16 slots (actually it has 8, as the macPro has). i've not heared about 4 GB mamory sticks so far, so the limit will be 16 GB ...
ad 2) that's hard to say and would need some in-depth reading of the chipset specs ... does throughput decrease if a second branch or channel is equipped with sticks of different size? i really don't know and only some nifty RAM benchmark test would give us numbers ...

but 8 GB seem to be enough - if you're really interested i'd try to take them out for testing and *feel* the difference - make sure you don't have any static electricity (get your wrist grounded) when touching the sticks and keep them in an antistatic bag in case you do so.
christian

Thanks - I figured 32 GB referred to a theoretical upper limit of the board, not the current Mac pro.

But what was the source of the info you pasted into your message, with the underlined warning not to mix sizes and speeds of RAM?

the source was the manual of a server motherboard ... as you can see even in the last line 8 slots stay empty. but wait - re-reading it by my own i see the underlined note: do not mix ..., so there might be a reason for it ...

Hey, CM-- thanks for the additional info. It is as revealing as it is confusing!! At least we're getting somewhere.

Of course this site from Macworld has some interesting info:

http://www.macworld.com/2006/08/firstlooks/macprofaq/index.php

Excerpt regarding L2 and system busses:

But no matter how you configure a Mac Pro, there are still a few constants: every model includes 4MB of shared L2 cache per processor and two 1.33GHz system buses, one per processor.

Excerpt comparing PCIx to PCIe:

In the Power Mac, each PCI Express slot had a set bandwidth, expressed in terms of lanes—the graphics slots was the fastest at 16x, with one 8x slot and two 4x slots as well. With the Mac Pro, Apple says that when you boot the computer after installing a new PCI Express card, the OS will let you choose the amount of bandwidth to dedicate to that slot. Apple told us that the total amount of bandwidth available to the PCI Express bus is less on the Mac Pro than on the Power Mac, but said the ability to direct that bandwidth as needed should make up for such a shortcoming. They also told us that there's more power (total wattage) available to the PCI Express bus, letting you power two Nvidia Quadro FX 4500 graphics cards.

As for the underlined "do not mix...", that was the first example of "do not" I've ever seen. It is clear that this is akin to the PPCs where the 8-slot riser card was introduced. Installing in matched pairs was made quite clear at that time, and it has certainly carried over.

Installing in 4s remains a quandary-- I've yet to find a "do not mix.." in terms of sticks in 4s... new (?) with 5000X. I am clear on the rule of using matched pairs of RAM sticks still applies with all these models.

While the 13% increase is not especially earth shattering, I still wonder about it, given that we spend SO much time squeezing out every micro-ounce of each computer's resources to accommodate VI Cube. That this 13% is focused only on the CPU, it remains to be determined how this increase benefits all the other fixed parameters involved with shuttling a demanding VI.

Right now, I'm looking at a 2.66 and a MacMini for about the same price as a 3G...

And yes--- the 32GB statement was a brow-raiser!!! [[[:|]]] [[[:|]]]

Thanks again!
JWL

One other observation-- correction on my part...

The developer note says "you SHOULD not" which is rather different in meaning than "DO not".

I don't know if Apple is trying to be polite by using the passive voice so often, but it is becoming an increasing source of confusion...

hehe ... if somewhere it reads *you should not* then i'm always taking it as a *do not* if i want to squeeze as much as possible out of *it* ...

PCI(X vs. e) total bandwidth ... total bandwidth of _what_ ... the bandwidth delivered to all slots simultaneously or the plain addition of bandwidth per slot times the number of slots ... i doubt the chipset of the PPC delivers more bandwidth than the chipset of the macPro ... adding simply up slots (eg. 64 bit x 133 MHz x 4 slots) is nonsense ... we all know that formerly gigibit network cards couldn't deliver full bandwidth (either because of sitting in a 32-bit slot or sharing the bus with other devices) because the PCI-bus itself has been the bottleneck ... if someone gives us figures he should also say on what such figures are based on or related to ...

in any case this keeps a theoretical discussion, because we don't have the choice to select between options.
christian

@cm said:

hehe ... if somewhere it reads *you should not* then i'm always taking it as a *do not* if i want to squeeze as much as possible out of *it* ...

PCI(X vs. e) total bandwidth ... total bandwidth of _what_ ... the bandwidth delivered to all slots simultaneously or the plain addition of bandwidth per slot times the number of slots ... i doubt the chipset of the PPC delivers more bandwidth than the chipset of the macPro ... adding simply up slots (eg. 64 bit x 133 MHz x 4 slots) is nonsense ... we all know that formerly gigibit network cards couldn't deliver full bandwidth (either because of sitting in a 32-bit slot or sharing the bus with other devices) because the PCI-bus itself has been the bottleneck ... if someone gives us figures he should also say on what such figures are based on or related to ...

in any case this keeps a theoretical discussion, because we don't have the choice to select between options.
christian

As always, cm, you nailed it. But this is typical of Apple. When reading fixes made with 10.4.9, their so-called "details" would always say fixed a bug with _x_ parameter, or better functionality with _y_--- but better than what? Fixed a bug is fine-- but what was the bug?

If we keep peeling back the layers of this onion, we'll get to the bottom of things sooner or later.

i'd say it is not as much apple, although they tend to make their descriptions as simple as possibel, but hyper-enthusiastic "writers" (please note the quotes) of certain magacines or online-publications who pick up single statements not understanding about what they are talking about. unfortunately this also applies to sales people too often ...

the machines itself are great, so i do not understand why such attampts for glrification are even needed ...

but to return to a real issue ... what soundcards are you considering to use? i have not been too lucky on searching for PCIe interfaces. roumors say the quadcore will offer a PCI-X slot again, because it seems there are not too much PCIe options on the market ...
christian

Maybe this was the slot change that broke the camel's back and the world is rebelling.

I personally will think *very* hard before I ever buy another expensive PCI card. It's just too much to keep up with. FireWire interfaces for me from now on.

@cm said:

i'd say it is not as much apple, although they tend to make their descriptions as simple as possibel, but hyper-enthusiastic "writers" (please note the quotes) of certain magacines or online-publications who pick up single statements not understanding about what they are talking about. unfortunately this also applies to sales people too often ...

the machines itself are great, so i do not understand why such attampts for glrification are even needed ...

but to return to a real issue ... what soundcards are you considering to use? i have not been too lucky on searching for PCIe interfaces. roumors say the quadcore will offer a PCI-X slot again, because it seems there are not too much PCIe options on the market ...
christian

I can understand Nick's feelings, but I've had my issues with Firewire lately. Even on the current MacPros, the FW ports all funnel into the single 33Mhz bus, and I'm using a Duende module-- which needs all the bandwidth it can get.

I'm giving the Apogee Symphony card a very serious look. The sound is incredible. One one computer I'm thinking of putting in one of the 16x interfaces and running it out to a modified MOTU 2408mk3 via ADAT for a start. Eventually, I'd like to go all Apogee-- but the MacPro and the first Apogee module and card come first.

I'm wondering if I can get away using their mini DAC on one of the computers and the Symphony plus 16x on the other....? Hmmm...

One nice thing about the 16x-- it has the same clock as their Big Ben!

i've just been tempted to reply to nick's post something like *this is kind of using a horse to move a car* ... i often noticed significant CPU-load using firewire obviously *only* for translating protocols ... besides that the firewire controller seems to be always an additional chip sitting *somewhere we found the place* on the motherboard design (physically and logically).

not sure if we're not wasting too much performance into this peticular detail using firewire ... i've also been glancing at the apogee models, their latency is outstanding low and i like their modular approach ... but the price is almost tasteless high.
on the other side a fireface (even the 400) is not the cheapest ...
christian

i think all these companies know that the choices are slim. When you are talking about RME or Apogee, suddenly some of the less expensive interfaces sound like walkie-talkies to my ears.

You other choice? Digidesign!! Did you say tastelessly expensive? [[;)]]

@cm said:

rumors say the quadcore will offer a PCI-X slot again, because it seems there are not too much PCIe options on the market ...

Now that's REALLY interesting! I wonder whether Digi would support a PCI-X HD card in an Intel Mac. Of course, if it's just one slot, it's not that interesting.

And... re my earlier post where I mentioned the processor meter of DP slamming in the red for my 17-instantiation VI test sequence, could the fact that I'm using a Profire Lightbridge be responsible? I.e., do such interfaces require a lot more processor juice than, say, the Symphony card?

And i agree, there must be SOME market for a no-frills PCIe digital audio card. Wonder if anything's in development.

cm: Like Borat? [:)]

JWL: There's also Metric Halo for high-end interfaces, and if you only need digital outs the M-Audio Profire Lightbridge sells for what, $450?

For PCs the RME cards aren't too expensive and the aging Frontier Designs cards are cheap. But I have two G5s with MOTU PCI-424 cards. While they're not *that* expensive (you can just upgrade the cards), that's two of them that will need to be swapped for PCI-e cards whenever I move to an Intel Mac. On top of that I have UAD-1 and a Sonnet SATA cards in my main machine.

PCI-express is definitely an advance, but I'm sick of expensive card upgrades. And I admit that it bothers me a little having an MBox instead of my Pro Tools MIX system. The decision to abandon MIX is supposed to have been because of the PCI changes too.

Neeeeeeeeeeigh! Giddyup!

@Nick Batzdorf said:

cm: Like Borat? [:)]

JWL: There's also Metric Halo for high-end interfaces, and if you only need digital outs the M-Audio Profire Lightbridge sells for what, $450?

For PCs the RME cards aren't too expensive and the aging Frontier Designs cards are cheap. But I have two G5s with MOTU PCI-424 cards. While they're not *that* expensive (you can just upgrade the cards), that's two of them that will need to be swapped for PCI-e cards whenever I move to an Intel Mac. On top of that I have UAD-1 and a Sonnet SATA cards in my main machine.

PCI-express is definitely an advance, but I'm sick of expensive card upgrades. And I admit that it bothers me a little having an MBox instead of my Pro Tools MIX system. The decision to abandon MIX is supposed to have been because of the PCI changes too.

Neeeeeeeeeeigh! Giddyup!

Yup-- I've got one 424 and that was about all I could stand.

I've only read two reports about Metric Halo and both were great. I don't know of anyone who has an MH interface, but would love to hear it. I'm looking for something more than just functionality-- but am looking to improve the output stage. My 2408mk3 just sounds rather lifeless compared to some of my colleagues' Apogee systems-- hence my current Apogee slant.

I'm aware of the M-Audio Lightbridge but am weighing my need for that first critical DA conversion stage.

I may have to do a side-by-side with Apogee and MH... thanks for the tip.

@plurye said:

And... re my earlier post where I mentioned the processor meter of DP slamming in the red for my 17-instantiation VI test sequence, could the fact that I'm using a Profire Lightbridge be responsible? I.e., do such interfaces require a lot more processor juice than, say, the Symphony card?

And i agree, there must be SOME market for a no-frills PCIe digital audio card. Wonder if anything's in development.

One element with DP that is starting to become a big concern with hefty VIs is the 64 buffer setting as a limit. Other DAWs are making good use of 32 buffer settings, and Apogee is demo-ing Logic with 40+ audio tracks and some 70 plugins running while tracking a processed guitar with *virtually* no latency.

Now, I love DP's GUI but there are some strange behaviors DP users endure that others don't. The question is at what point those behaviors are no longer worth tolerating. I'm not at the point yet of tossing it out, but am placing my hopes in a new Intel to do a better job at shuttling audio without breaking too much of a sweat.

JWL -

That's pretty cool. Love to know if anyone's tried to run a Vienna VI-heavy DP sequence on a Mac Pro using a Symphony card with "virtually no latency". A setting of 64 would not fly with the Lighbridge on a sequence with lots of VIs! 'Twould be nice to see how DP and Logic compare efficiency-wise with the same hardware. Used to use Logic - DP interface is so much more straightforward; like you I'd hate to give that up. But i may have to as well.

PL