PCIe configuration

[Nicos Ambatzis]

I know that I am repeating a subject so many times discussed in the past, but I would like to find a way out even not the best one, but good enough for the time been until Apple announces the new Mac and because we are in very difficult times (budget wise). Using an early 2008 Mac Pro with 32GB ram, under the following configuration :

slot 1 GTX 570 16
slot 2 RedRocket 8
slot 3 DeckLink Extreme 3D 4
slot 4 ATTO 680 8 (the required configuration)

What will be the better choice to set the Expansion Slot Utility inside the Mac to have the 'best'' (compromising) results running Resolve (even the Lite one).
The choices are :

A..... 16... 1... 1... 8
B..... 16... 1... 4... 4
C...... 8.... 8... 1... 8
D...... 8.... 8... 4... 4

Thanks in advance.

 

[Jeff Kilgroe]

This is a Mac Pro 1,1 or 2,1 model. So even though you bought in '08, it's really the previous 2006 edition. The 2,1 spec bump in 2007 was just an EFI update to account for a couple new CPU options and to offer the first 8-core configuration. It's often referred to as the Mac Pro 8X within Apple's tech docs for some odd reason. But the 2006 edition logic board (1,1 and 2,1 models) is the only one with configurable PCIe.

OK, the problem here is that there are 24 lanes total, so not enough to go around. But wait, that's not the only problem, your Mac Pro only has PCIe v1.1 slots, no PCIe v2.0 support. You have 3 cards in your system that are PCIe v2.0 cards. So even if you give those v2.0 cards the proper number of lanes, they can't run any faster than half speed. Just be aware of that. The RED Rocket is a v1.1 card, the others are all v2.0. PCIe v1.x lanes run at 250MB/s, v2.x lanes run at 500MB/s.

That also leads me to the question of the GTX 570... Do you have this card installed and working??? If so, consider yourself lucky. If you're planning to buy this card to install in this system, don't.

It pains me to say it, but Option D is the best option here. You can then install your video card in slot 1 where it fits -- it will run at half speed and half the number of supported lanes. The Rocket in slot 2 and it will run at full bandwidth. The Decklink card in slot 3, it will have the proper number of lanes, but they will be running at half speed. And finally the H680 in slot 4. 4 lanes for the H680 is just fine in most all situations. It truly doesn't need 8 lanes, unfortunately it will also be running at half speed because it's a v2.0 card as well.

That's really the best you can do with this system. In many ways, you're pushing this system a bit too far beyond what it was designed for, it's just an old system at this point.

All that considered, the biggest bottleneck you will have in this system is actually not the PCIe slots, but the RAM, which runs in a dual-channel configuration at 667MHz. Or only 30% as fast as the 2010 Mac Pro. There is also the question of how you have your internal hard drives configured and what potential bottlenecks you may have there.

 

[Nicos Ambatzis]

Fist of all I would like to thank you very much for replying to my mail and your consideration to my problem.
My Mac Pro is 2.1 model A1186, as you said, a 3.0Ghz (Quad core X5365), Clovertown, base memory 1GB PCZ2-5300 DIM with 32GB ram, one PCIe v2.0 x 16 2.5Gb/s and the rest with the configurations I mentioned in my previous mail, running Version 10.6.8. I do not have the GTX 570 (I have a Quadro FX 4500), but I am thinking about the GTX as the most approachable CUDA solution at the moment which card I can use with the new Mac I presume. I am afraid if I still want to run Resolve there is no much I can do. The question is how functional I can be with Resolve, up to what extend I can use it. In this limited situation what you think is the best way to go without buying another Mac and sale it later on etc.etc.??? The idea of mine trying to go with a GTX570 and the Blackmagic card, the RR and the ATTO using the configuration C is it better or worse than the D one?? Thanks again Jeff.