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Author Topic: Mac Pro 2,1 PCI-Express speed ?  (Read 2897 times)
SMIKX
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« on: June 17, 2015, 09:15:50 AM »

Hi,

I've done a lot of searching but still cannot get a clear answer re Mac Pro 2,1 video card PCI link speed.

I have seen references to this in Netkas's forums but at the time didn't think it was so important ( foolish).

I currently have a flashed Vapor-X HD 5870 in my 2,1 MP.  ( EFI boot screens OK with DVI - VGA )

In Sys Info/PCI Cards it shows the link speed as 2.5 GT/s.

Is this a built in limit for the 2,1 Mac Pro ?

My questions :

1. Which Mac Pro model will yield the maximum PCI speed with my present 5870 ( is that speed 5 GT/s ?

2. Is anyone getting the full 5 GT/s & if so what is your setup.

Many thanks in advance.

EDIT : Just found the answer here : https://forums.creativecow.net/thread/364/1982

          I'll be getting a Mac Pro 4,1

« Last Edit: June 17, 2015, 09:20:14 AM by SMIKX » Logged

Mac Pro 4,1 upped to 5,1 Dual Quad Core 2.93ghz 17Gb 480Gb SSD TRIM enabled.
Radeon R9 270X 2Gb EFI on DP to HDMI. DVI to DVI.
10.12.5 - 10.9.5 - 10.12.5 - 10.6.8 - Win 7 not Bootcamp. 
AREA 2 port USB 3.1 & Inateck USB 3.0 4 port in OS X 10.9.5.
Fl0r!an
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« Reply #1 on: June 17, 2015, 12:46:06 PM »

Your Mac Pro has PCIe 1, so 2.5 GT/s is maximum. This does not limit the computional power of your GPU however, just the bandwidth for transfering data.

Additionally, most flashed PC cards will only run with 2.5 GT/s even on MacPro3,1+ without further modifications (e.g. removing resistor on the PCB or additional mods in the EFI).
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SMIKX
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« Reply #2 on: June 19, 2015, 01:59:37 AM »

Yes, I recall seeing "having to cut with a hobby knife . ." comments here with dread.

But going from a MP 2,1 to a 4,1 will give me 64 bit ( plus faster EFI'ed GPU's  in Yosemite ) and also a 4,1's firmware can be upped so seeing that I can get a 4,1 MP in very good condition here for about ¥75,000 with at least 8 Gb RAM I will definitely be better off.

In any case, thank you for reminding me that I definitely do not want to cut traces on a video card.
Logged

Mac Pro 4,1 upped to 5,1 Dual Quad Core 2.93ghz 17Gb 480Gb SSD TRIM enabled.
Radeon R9 270X 2Gb EFI on DP to HDMI. DVI to DVI.
10.12.5 - 10.9.5 - 10.12.5 - 10.6.8 - Win 7 not Bootcamp. 
AREA 2 port USB 3.1 & Inateck USB 3.0 4 port in OS X 10.9.5.
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