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crackajacka77

macrumors newbie
Jun 3, 2022
18
1
Lol. Just played a few games and there is literary minimal difference between an RX580 and a RX6800. This card is so severly bottle-necked by the MacPro5,1 CPU and ancient RAM DDR3 RAM. There's absolutely no need to get an RX6x00 card for a CPU that old. Stick to the RX580s.
 
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tsialex

Contributor
Jun 13, 2016
13,454
13,601
Lol. Just played a few games and there is literary minimal difference between an RX580 and a RX6800. This card is so severly bottle-necked by the MacPro5,1 CPU and ancient RAM DDR3 RAM. There's absolutely no need to get an RX6x00 card for a CPU that old. Stick to the RX580s.

I'd think that is fair to say that the majority of people here interested in RX 6800/6900 XT GPUs with a MacPro5,1 are using the GPU for converting/colour grading/compressing video or running GPU compute apps, not exactly gaming with the MacPro5,1 which is really bottlenecked by the missing AVX/AVX2.0 instruction sets and the low bandwidth of DDR3 when compared to high-end DDR4 and DDR5.
 

apeezyfosheezy

macrumors newbie
Oct 12, 2023
1
0
I flashed my msi rx 6600xt card in windows 10 and am having issues on my mac pro 5,1 using open core legacy patcher 1.01 running sonoma and whenever it boots I get the boot picker and see the black loading screen then the screen goes blank. I have no idea what’s going wrong! I followed the steps exactly and don’t think it’s flashes incorrectly. I previously had an rx 580 working just fine in sonoma. I can also boot into recovery mode with the 6600xt with no issues and can see the screen without a problem so I’m stumped! Please help!
 
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tsialex

Contributor
Jun 13, 2016
13,454
13,601
I flashed my msi rx 6600xt card in windows 10 and am having issues on my mac pro 5,1 using open core legacy patcher 1.01 running sonoma and whenever it boots I get the boot picker and see the black loading screen then the screen goes blank. I have no idea what’s gojng wrong! Please help!

NAVI GPUs are not supported by OCLP with anything but Monterey.

 

h9826790

macrumors P6
Apr 3, 2014
16,656
8,587
Hong Kong
Lol. Just played a few games and there is literary minimal difference between an RX580 and a RX6800. This card is so severly bottle-necked by the MacPro5,1 CPU and ancient RAM DDR3 RAM. There's absolutely no need to get an RX6x00 card for a CPU that old. Stick to the RX580s.
This is heavily depends on the games and settings.

If you go 4K and max settings. On most current AAA games, 6800 should show a huge performance gain from RX580.

At least on my cMP. From RX580 to 1080Ti / Radeon VII is clearly a huge difference in gaming on most games (definitely not ALL. e.g. There is no gain in the game Thief, which is very CPU single thread limiting).
 
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Opinionandrants

macrumors newbie
Jul 2, 2012
7
1
What cables do you use for 6600 XT with two connectors? Is it 8 pin to 6 pin then 6 pin to 6 pin?

I have a 6600 XT with only one 8 pin and I use a 8 pin split to 6 pin.
 

macsoundsolutions

macrumors regular
Jan 12, 2010
205
101
This is heavily depends on the games and settings.

If you go 4K and max settings. On most current AAA games, 6800 should show a huge performance gain from RX580.

At least on my cMP. From RX580 to 1080Ti / Radeon VII is clearly a huge difference in gaming on most games (definitely not ALL. e.g. There is no gain in the game Thief, which is very CPU single thread limiting).
Agreed I have been playing 4k max settings with my RX6800XT and it performs really well. Resident Evil 4 with ray tracing on and still getting over 80FPS on average.
 

avro707

macrumors 68020
Dec 13, 2010
2,263
1,654
Agreed I have been playing 4k max settings with my RX6800XT and it performs really well. Resident Evil 4 with ray tracing on and still getting over 80FPS on average.
I use a 6600XT in my 6 core 3.46ghz 5,1 and Zwift runs at highest detail and 4K pegged at 60fps in nearly all the worlds.

Even the heavy on frame rates Makuri world runs nicely. The old RX580 couldn’t do that. The 6600XT also seems to run a lot cooler and with less fan noise.

That computer is dedicated to running Zwift, permanently connected to a 4K 55” TV screen.
 
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Macschrauber

macrumors 68030
Dec 27, 2015
2,979
1,487
Germany
What cables do you use for 6600 XT with two connectors? Is it 8 pin to 6 pin then 6 pin to 6 pin?

I have a 6600 XT with only one 8 pin and I use a 8 pin split to 6 pin.
This is discussed dozen times, here.

8 pin is 150 Watt rated, 6 Pin is 75 Watt rated. In Real world Mac Pro shuts down above 110 Watts hard.

Use a 8 pin to double 6 pin cable to get 2x75 Watts.
 

Opinionandrants

macrumors newbie
Jul 2, 2012
7
1
This is discussed dozen times, here.

8 pin is 150 Watt rated, 6 Pin is 75 Watt rated. In Real world Mac Pro shuts down above 110 Watts hard.

Use a 8 pin to double 6 pin cable to get 2x75 Watts.
I am using that. I’m asking about the 6600 XT variant with a 8 pin and 6 pin.
 

Graphix67

macrumors newbie
Oct 23, 2023
1
0
Just a quick question (I went through the posts for the answer but couldn't find it). If I want to install an RX 6800XT in a macpro5,1, do I need to flash the card with the syncretic patch if I only used the Mac Pro with Windows?

Thx!
 

macsoundsolutions

macrumors regular
Jan 12, 2010
205
101
Just a quick question (I went through the posts for the answer but couldn't find it). If I want to install an RX 6800XT in a macpro5,1, do I need to flash the card with the syncretic patch if I only used the Mac Pro with Windows?

Thx!
The Mac Pro 5,1 will not boot unless the card has been flashed first. OS doesn't matter.
 
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macsoundsolutions

macrumors regular
Jan 12, 2010
205
101
Still no drivers that work without AVX 2.0.
So I guess it's the end of the road. Just updated to 12.7.1 with MLOC 0.9.5
 

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equals

macrumors member
Jun 24, 2018
34
19
So I guess it's the end of the road. Just updated to 12.7.1 with MLOC 0.9.5
Guys from Dortania say they are still trying to implement support for Navi GPUs with OCLP:
We're recently received an AMD RX 6600 donation, so hopefully in the future the project can support AMD Navi with pre-Haswell Macs. However, no time estimates can be given.
They did it for other architectures so there is still some hope.
 

macsoundsolutions

macrumors regular
Jan 12, 2010
205
101
Guys from Dortania say they are still trying to implement support for Navi GPUs with OCLP:

They did it for other architectures so there is still some hope.
We can only hope but that post is pretty old. the issue is even if they get it working the 5,1 it still wont work with games and software that require AVX2 like the new versions of FCP and Logic most likely.
 

Opinionandrants

macrumors newbie
Jul 2, 2012
7
1
So for video cards with 8pin and 6pin, do I get a straight 8pin to mini 6 pin and then 6 pin to mini 6pin?

My Power Color Red devil 6600XT is on the way and it has a 8pin and 6pin for power.

I’m currently using a Sapphire Nitro+ 6600 XT that only has one 8 pin that is split to two mini 6 pin.
 

equals

macrumors member
Jun 24, 2018
34
19
We can only hope but that post is pretty old. the issue is even if they get it working the 5,1 it still wont work with games and software that require AVX2 like the new versions of FCP and Logic most likely.
Sure. I just meant there is some kind of hope for Ventura/Sonoma to work with 6000 series AMD cards without AVX2 in the future via OCLP.

As for AVX2 itself, there is just a ghostly hope that @Syncretic will finish his emulator. But... ages have passed since the most recent info on this project.
 
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Rimmsi

macrumors regular
Jun 19, 2021
199
68
Czech Republic
Hi all, is it safe to run MacOS Catalina with RX 6900 XT and W5700X? Is it possible to install Catalina using Internet Recovery with both cards? Thank you.
 

macsoundsolutions

macrumors regular
Jan 12, 2010
205
101
Hi all, is it safe to run MacOS Catalina with RX 6900 XT and W5700X? Is it possible to install Catalina using Internet Recovery with both cards? Thank you.
"If you've installed macOS Big Sur 11.4 or later, you can use AMD Radeon RX 6800, AMD Radeon RX 6800 XT, and AMD Radeon RX 6900 XT." The 6900XT might get video output with Catanlina but you won't get acceleration without 11.4 or later. Also you want to make sure the card is not too long as some versions don't fit in the 7,1.
 

okboomer

macrumors newbie
Nov 6, 2019
8
8
Just installed a RX6900 XT in my Mac Pro 7,1.

Using displayport with a InnoCN 27m2v monitor

Windows bootcamp gives me 4k 120hz VRR
OSX only gets me 60 fps no VRR

Anyone knows how to solve the issue?
Hey everyone, might already have been discussed but Sonoma actually fixes this. I saw someone saying that it was rumored so I took a bet and upgraded to Sonoma and what do you know?

Screenshot 2023-12-15 at 15.56.55.png


3840x2160@144Hz in HDR with no subsampling and VRR on the RX 6900 XT.

Screenshot 2023-12-15 at 16.20.33.png


I'm so happy!
 
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