All PCI-X line-up next time?

PCIe is not compatable with PCI.

If Apple did it right, right meaning what's right for customers, they would have a PCIe x16 slot for graphics cards, a PCIe x2/x4/x8 slot, a 133 MHz PCI-X slot and a 33 MHz PCI slot for the next Power Mac. Actually, the PCI-X slot should be able to be changed to a 33 MHz PCI slot, the PCIe x16 slot should have two slots worth of space reserved for itself, and their should be 2 PCIe x16 slots. But this is Apple we're talking about. Backwards compatibility isn't a huge concern for them.

Anyways, I predict what you are hoping for:

1 PCIe x16 slot and 3 PCI-X slots on for the high end.
1 PCIe x16 slot and 3 PCI slots for the low end.

This would be the minimal investment, outside of better CPU and memory support, for the next rev. AGP is replaced with PCIe, everything else stays the same. Same Hypertransport PCI/PCI-X bridge chip, same I/O chipset.

Computers won't be all PCIe for another product cycle or so.

Well he is not totally wrong, as to your problem you have two approaches to dealing with it.

One is to buy a system that you know works now. Get your new hardware and enjoy it mode of thinking here. Following a known upgrade path is certainly a little easier on the mind than waiting for hardware we don't know about at the moment.

The other approach is to wait until the new hardware is delivered so that you can see for yourself how it is configured. Keep on the ball just in case the new hardware is not what you want and grab an older machine as they are disocunted in the market.

The problem is that new hardware may very well have trouble with your software even if it supports the slot in question. You won't really know until the software and hardware is tested together on the new hardware. So even if the slot is there, you probally will have to wait for verification from your hardware vendor as to compatibility.

No one really seems to know what Apple is going to do with respect to PCI-Express. At least nothing has been published. My feel for the situtation is that they have to move to PCI-Express real soon now as their credibility depends on it. How they implement that is the interesting question of course and is in a nutshell the focus of this thread. The reality is no body knows.

We can geuss however. My geuss is that they will maintain a couple of the PCI-X low speed slots and provide PCI-Express for the balance of the system I/O. One PCI-Express slot would be there to accommodate a wide graphics card at 16X. At least one more additional 16X slot would be supplied and the balance either 1 or 8x slots. That is a guess of course, but the reality is that it (the new PowerMac platform) will be introduced on new silicon, so as stated above no one really will know if your hardware will work on the system. Probally not what you wanted to hear.

You might want to seriously think about scrapping that card of yours and to wait for something newer to come on the market.

Dave

If the Power Mac is going to be as big as it is, Apple has no excuse for not making it a 6 slot machine. None of this nonsense about the PPC970 being oh-so-hot or the 'thermal zones.'

a six slot Mac should be:
(1) 16x PCIe
(3) 1x PCIe
(2) PCI-X 133 MHz

a four slotter should be:
(1) 16x PCIe
(1) 1x PCIe
(2) PCI-X

If you need the cutting edge PCIe slots, you'll get the big box. Two legacy slots is enough.. It's not like they had combo built-in NuBus/PCI or SCSI/FireWire Macs. When FireWire appeared on the B&W G3, SCSI was was gone (only available as a CTO PCI card).

There's also the possibility of using something like an HTX riser/mezzanine board for tru customizability...

What I see happening is this:

The northbridge will be integrated with the G5. The northbridge is already produced on the same process as the G5, so it shouldnt be tricky. Im not sure how they would handle a dual cpu in this situation - perhaps a PI bus going to the second cpu, which might have its own memory. AGP would be dropped, and the main off chip bus would be Hypertransport.

Then Apple can use the same technique that Sun use in their AMD workstation. The expansion slots would located on a seperate board, and that board can be selected based on need, and even upgraded in the future. The board would be connected with hypertransport, and would have on it the requisite chipsets - AGP, PCI, PCIe - that the user needed. As for number of slots, well there is only so much space in the case. I dont see it getting bigger. What Apple could do is integrate an AGP graphics card into the expansion card, and then provide a 16x PCIe slot for the user to do as they see fit with ( you can put a 1x card in it if you need to ). They could even put a PCIe chip on the expansion board, and then support SLI with a second add in card.

I guess the reason for having as few expansion slots in the PowerMac as we do has to do with the power supply: Every slot must be considered when planning the power supply's size. And oversized PUs work very inefficiently when not fully used.

PCIe and especially with SLI will be problematic power-wise. Apple sill uses that little AGP Pro knob to feed the high-end cards with additional power. Are there similar provisions in the PCIe standards?

Hi Eugene;

While I do agree without about the six slotter capability I suspect that Apple will arrainge the slots differently on both models.

I suspect that Apple will do one of two things with respect to graphics performance. They will either deliever a machine with two 16X PCIe slots or they will develope a PCIe graphics card with two GPU's on it. Apple is slipping with respect to its acceptance as a graphics machine and they need to address that public perception, I think Apple knows that they need to address this issue.

The advantage of having 2 16X PCIe slots is that one can otherwise be marketed as a slot for high performance I/O cards. So for people not looking for bleeding edge graphics they still have a performance option.

As to the rest of the slots I don't see Apple giving up on PCI-X anytime soon either. Then it becomes a question of mix which could be anybodies geuss. I'm thinking one PCI-X slot with the balance being PCIe.

Apple does need to get on the ball with respect to the moterboards. I have this ugly feeling though that they will wait until the developers conference to deliver PCIe. We are likely to see the PowerMacs delivered with a nice speed boost and nothing more come Janurary. The developers conference would be due to signifcant changes made that are developer related. I could be wrong, actually hope that I'am wrong, as it would be Apples best interest to be in the PCIe business when everybody else is.

Dave

No. I don't think that, the engineering, is the problem. The real reason is Apple wants it that way. They are trying to straddle workstation and prosumer markets, and their PowerMac G5 with 4 slots is the magic number that pops out when the bean counters are done.


PCIe x16 will support 75 Watt graphics cards. AGP 8x supports 25 Watts. AGP 8x Pro supports 50 Watts. Apple apparently has AGP 8x Pro in its Power Mac G5.

There also an AGP 8x Pro110 implementation that supports 110 Watts, but I haven't seen a computer with this yet.

If Apple wants to have a powerhouse graphics machine, and to date they really haven't wanted to, they would have to have at least 2 PCIe x16 slots for SLI or multi-rendering. With the large heat sinks and fans of high performance graphics cards, two of them in an SLI configuration would take up 4 slots of space, at minimum. That's the entire expansion slot bay in the current Power Mac G5. A Power Mac with 6 usable slots, 2 PCIe and 4 others, would require double the volume seen in the Power Mac G5.

I think it is reasonable for Apple to make people choose between SLI and flexibility. The PCIe 16x slots can each be paired with a 1x slot. If you want to use cards that have huge heat sinks then you loose the 1x slot. If you can cope with having slower cards, eg: the 6600, then you can still have the SLI, and the two obscured slots.

It would be pretty straight forward to pair each 16x with a 1x and then put two PCI-X slots above them ( bigger case required ).

SLI is really only addressing a nich market. While I would like it I don't consider it a feature that would generate an increase in sales. SLI really only makes sense when utilized in two ways.

1. Buying one card and then upgrading to a second card in the future.

2. Buying the fastest cards available and utilizing both of them in SLI config.

I'm seeing far too many people talk about using GT6600s in SLI and that makes no sense. Just buy the 6800 and then double up later.

I'm interested in seeing how Apple will handle this transition from PCI-X to PCI Express. 6 slots is expensive but they may have to do that to smooth the transition out some. I think we see their plans come MWSF.

Grr! The bandwidth provided by PCI-e is only needed for graphics cards. There isn't an audio interface card on the market that needs anything faster than 33MHz PCI, and AFAIK there aren't any being made.

What we have been seeing, as the manufacturers relentlessly push these bleeding-edge busses on us, is that people who have investments in PCI hardware (some cards cost more than these computers, BTW) simply keep using old hardware. Down the road, I suppose we'll find Firewire or some other solution. The new-fangled slots remain empty and the users can't upgrade. That fits my definition of technological arrogance.

There isn't any reason on earth why a modern G5 computer can't have one or two PCI (not PCI-e, not PCI-X) slots in it. None whatsoever. PCI is plenty fast enough for virtually everything but graphics and high-speed network cards.

What if I want a freaking fast RAID setup? Those puppies can max out several PCI busses at once.

You actually can have a PCIe 1x slot and a PCI slot coexist in the same slot space.



But this is Apple we are talking about. They have technology arrogance up the wazoo...

Not true at all. There ae a number of I/O adapters that are performance limited due to PCI. Granted many of those are for advance usage that most people here don't need but none the less there is big demand for higher performance. It is interesting to note that some of the first PCI-Express cards on the market where not Graphics cards.

That well may be the case, I really don't know. The reality it that implementation depends on a number of factors, some engineer some place could decide that the faster bus offers him an advantage with audio.

I think your perspective is wrong here. The drive for higher performance buses come from the card manufactures. There is a big demand for high speed buses to handle I/O.

Now that doesn't mean that manufactures should support the old buses. Hopefully, with the software compatibility between these various PCI implementations, the old PCI slots will remain around for a long time.

Well I hope myself that doesn't happen. There will always be a need for computers with expansion slots. I do see a problem where Apple might say that that is not part of their targetted markets though. Apple pretty much thumbs their nose at people's expansion needs, pushing firewire and USB, in half their line up now. Not a good thing if you ask me.

While I can agree on the need to keep PCI around for a long time there are demands out there beyound graphics and networking for high speed interfaces. In any event not every PCI-Express slot is a high speed one. PCI-Express will lead to signifcant improvements in form factors for PC's, in the long run it is a good idea.

At work I currently have the opposite problem. We have special machines that use ISA cards on i86. The manufacture is not willing to upgrade the I/O hardware so I'm destined to search for old PC hardware everytime one of these breaks down. So I see both sides of the story. Hopefully Apple offers a rational approach to PCI-Express.

Isn't PCI-X backward compatible with PCI? Can't you just use the card anyway. I thought you could.