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ng7apoc

macrumors member
Original poster
Jul 29, 2010
79
5
UK
..When using all 4 Slots?

What I mean is that if I were to purchase a refurb 2009/10 Mac Pro and in addition to the Video card I were to fill the remaining 3 slots with a 2 port USB 3.0 card, 2 port eSATA card and a SATA 3/6GBps RAID card would I see any bottleneck in bandwidth if all 3 cards were in full use?
 
No.

Individual slots have their own restrictions, but they're all independent.
 
Since 2008 Mac Pro (3.1), PCIe is v2.x.

Specs for x1 bandwidth (V2.x) is 500 MB/s (5 Gb/s).
Slots in Mac Pros are x16, x16, x4 and x4, so only limitation is bandwidth per slot.
 
Last edited:
The PCIe slots do not share bandwidth.

Correct me if I'm mistaken, but what I understood about the way PCIe slots are wired is as following:
On the 2009/2010 models, 36 lanes are available. 16 wired for slot 1, 16 wired for slot 2, and the 4 remaining being wired to slot 3 and 4.

So slots 3&4 cannot run both at full 4x bandwidth at the same time.
 
Correct me if I'm mistaken, but what I understood about the way PCIe slots are wired is as following:
On the 2009/2010 models, 36 lanes are available. 16 wired for slot 1, 16 wired for slot 2, and the 4 remaining being wired to slot 3 and 4.

So slots 3&4 cannot run both at full 4x bandwidth at the same time.

This is correct I believe..
 
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