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Mic-M4c

macrumors member
Jan 9, 2015
80
13
Paris, FRANCE
If you don't need backwards compatibility with Mojave, a RX 5700XT can also be used with Catalina/BigSur/Monterey.

You will need an eVGA PowerLink to balance the two power rails, btw.
Is the RX 5700XT more powerful than the Radeon RX 580 8GB non-OC ?

eVGA PowerLink is far far too complicated for me and dangerous because I'm not an electrician but a plug-and-play guy :(
 

tsialex

Contributor
Jun 13, 2016
13,454
13,601
Is the RX 5700XT more powerful than the Radeon RX 580 8GB non-OC ?
Yes.
eVGA PowerLink is far far too complicated for me and dangerous because I'm not an electrician but a plug-and-play guy :(
You are mistaken the eVGA PowerLink for the Pixla's mod. Nothing is more plug and play than the PowerLink, it's literally just to select the correct output for your GPU, plug the cables, install the PowerLink on the GPU power inputs.
 

tsialex

Contributor
Jun 13, 2016
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Do you have any link for such "easy" installation please ?


There are several other posts with examples over the Mac Pro forum, use the search if you still have doubts.
 

Mic-M4c

macrumors member
Jan 9, 2015
80
13
Paris, FRANCE
Ok !
So I just have to plug the EVGA PowerLink on the graphic card and then plug the power cables on the EVGA PowerLink ?!
OMG !
 

tsialex

Contributor
Jun 13, 2016
13,454
13,601
Ok !
So I just have to plug the EVGA PowerLink on the graphic card and then plug the power cables on the EVGA PowerLink ?!
OMG !
Yes, you can install RX 580/RX 5700XT/Vega 56 with an EVGA Powerlink and you won't have SMC shutdowns when in load.

EVGA Powerlink won't help you if the GPU requires more than 220~230W with load, even if it's an instantaneous peak. Anything over and you need a Pixla's mod.
 

Snahbah

macrumors regular
Jun 28, 2008
105
51
Your answers are very interesting +++ ?? but why so few people use then EVGA PowerLink ? :(
I hope the EVGA PowerLink box includes the necessary cables.
Get the right card and you won’t need this. Just power from the motherboard to the card. I’ve got 2 x Gigabyte 5700XTs one powered from the motherboard and the other directly from the PSU (mod). Because the draw is low from the Gigabyte cards I’ve never had a problem.
 

Mic-M4c

macrumors member
Jan 9, 2015
80
13
Paris, FRANCE
OK

So, if I don't wanna make a Pixla's mod for a Radeon VII, I can buy a Gigabyte 5700XT (Catalina+) without anything else ?

Gigabyte 5700XT (Catalina+) is better than RX 580 (Mojave+), RX 590 (Mojave+) and Vega 56/64 (Mojave+) ? Correct ?
 

tsialex

Contributor
Jun 13, 2016
13,454
13,601
Get the right card and you won’t need this. Just power from the motherboard to the card. I’ve got 2 x Gigabyte 5700XTs one powered from the motherboard and the other directly from the PSU (mod). Because the draw is low from the Gigabyte cards I’ve never had a problem.
Just because works for you, don't mean that is gonna work for everyone else. Even the non XT version, RX 5700 instantaneous (spike) maximum power draw is over 200W, it's a card right on the limit of the SMC shutdown, works for some, shutdown with load for others.

P86yjZkCaj2cgVtLrqcTY3.png


The 264W spike of the RX 5700XT is way over the Mac Pro SMC shutdown:

fHeFpwGnjNTn7uHXmgBK7H.png
 
Last edited:

tsialex

Contributor
Jun 13, 2016
13,454
13,601
OK

So, if I don't wanna make a Pixla's mod for a Radeon VII, I can buy a Gigabyte 5700XT (Catalina+) without anything else ?

Gigabyte 5700XT (Catalina+) is better than RX 580 (Mojave+), RX 590 (Mojave+) and Vega 56/64 (Mojave+) ? Correct ?
This become circular, you already have every answer to your questions.
 

Mic-M4c

macrumors member
Jan 9, 2015
80
13
Paris, FRANCE
Yes I think you're right.
Gigabyte 5700XT (Catalina+) is better with EVGA PowerLink to prevent any shutdown.
RX 580 (Mojave+) and RX 590 (Mojave+) don't need EVGA PowerLink but are a little less efficient.
 

tsialex

Contributor
Jun 13, 2016
13,454
13,601
Yes I think you're right.
Gigabyte 5700XT (Catalina+) is better with EVGA PowerLink to prevent any shutdown.
RX 580 (Mojave+) and RX 590 (Mojave+) don't need EVGA PowerLink but are a little less efficient.
Incorrect, RX 590 have a peak power draw of 245W, with 300.4W momentous spikes. It's not a card to use without PowerLink load balance.

LeU4SmPqYg4hFLn8HtdAoM.png
 

Snahbah

macrumors regular
Jun 28, 2008
105
51
Just because works for you, don't mean that is gonna work for everyone else. Even the non XT version, RX 5700 instantaneous (spike) maximum power draw is over 200W, it's a card right on the limit of the SMC shutdown, works for some, shutdown with load for others.

P86yjZkCaj2cgVtLrqcTY3.png


The 264W spike of the RX 5700XT is way over the Mac Pro SMC shutdown:

fHeFpwGnjNTn7uHXmgBK7H.png
Not all 5700XTs are the same. There’s a huge disparity between power draw between card - as I said. I’m am running a Gigabyte with zero issues at full load for hour after hour and never had an issue running one of these cards powered from the board.

I’m guessing you don’t run a Gigabyte 5700XT (the newest card that the cMP will run) in a 5.1 as you’d be better informed if you did.
 

Snahbah

macrumors regular
Jun 28, 2008
105
51
OK

So, if I don't wanna make a Pixla's mod for a Radeon VII, I can buy a Gigabyte 5700XT (Catalina+) without anything else ?

Gigabyte 5700XT (Catalina+) is better than RX 580 (Mojave+), RX 590 (Mojave+) and Vega 56/64 (Mojave+) ? Correct ?
You are correct. This is what I run (full load Octane renders for long hours) and I’ve never had a problem with my Gigabyte 5700XT powered from the motherboard.

I wanted a pair of them but then I had to do the mod. Not that hard but you have to have patience.

Good luck to you.
 

Mic-M4c

macrumors member
Jan 9, 2015
80
13
Paris, FRANCE
I don't want you to argue and be in a bad mood.
But tsialex and you have given me very good informations.
??
I will give a look to eBay and french sellers for those cards.
 

Dayo

macrumors 68020
Dec 21, 2018
2,257
1,279
Incorrect, RX 590 have a peak power draw of 245W, with 300.4W momentous spikes. It's not a card to use without PowerLink load balance.
How about RX 580? I run mine naked but can't say it has been particularly stressed.

install RX 580/RX 5700XT/Vega 56 with an EVGA Powerlink and you won't have SMC shutdowns when in load.
 

tsialex

Contributor
Jun 13, 2016
13,454
13,601
How about RX 580? I run mine naked but can't say it has been particularly stressed.
The first thing is your workflow, if you don't game/render/compute with your GPU, it's plausible that your GPU will never enter PowerPlay settings and never have the full power draw.

For most non-OC RX 580 models, it's relatively safe to use with a non marginal backplane/PSU combo without any mods - remember that the capacitors of your early-2008 PSU were made around 2007/2008 and 14+ years later the capacitance is considerably reduced.

If you have a card that the PowerPlay settings are moderate and if your backplane/PSU are still healthy enough, should work fine without any SMC shutdowns, but for OC models all bets are off.

For example, Tom's Hardware tested a Sapphire Nitro+ and even ignoring the absurdity of the momentous spikes over 340W (just for the GPU, powered independently of the rest of the PC by lab power supplies), the median power requirement when in load is over the SMC shutdown.

N5VJRrWmqTm7mK8QzwNd4B.jpg
 
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Mic-M4c

macrumors member
Jan 9, 2015
80
13
Paris, FRANCE
Hi back,
RX 5700 XT is said to be compatible for Catalina and later (Catalina+).
Does this mean that I cannot boot into Mojave (my OpenCore bootable SSD) but I can boot on Catalina, Big Sur and Monterey WITH the OpenCore bootscreen at least ?
Thx
 

tsialex

Contributor
Jun 13, 2016
13,454
13,601
Hi back,
RX 5700 XT is said to be compatible for Catalina and later (Catalina+).
Does this mean that I cannot boot into Mojave (my OpenCore bootable SSD) but I can boot on Catalina, Big Sur and Monterey WITH the OpenCore bootscreen at least ?
Thx
I've explained this before, no need to confirm it:


Apple supported the NAVI 1x GPUs for the first time with Catalina 10.15.1 and newer macOS releases.

When using OpenCore pre-boot support configuration for UEFI GOP GPUs, you can boot unsupported macOS releases with the GPU, via the fail-safe EFI drivers, but the display is completely un-accelerated, only some resolutions are available (not all displays work) and is basically only useful for diagnostics.

Without OpenCore, you can't boot Mojave with any NAVI card.
 

Mic-M4c

macrumors member
Jan 9, 2015
80
13
Paris, FRANCE
… so when computer arrive in the macOS system, every material acceleration is ok/normal ?
I then can boot into Recovery Mode with no acceleration ?

I don't know all these very technical considerations :(
 
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