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Spacedust

macrumors 65816
Original poster
May 24, 2009
1,005
160
Radeon RX6800 16 GB is now the fastest card for Mac Pro 4,1/5,1 with standard EFI boot screen. You can see EFI boot screen even without any HDD/SSD installed at all.

macOS Monterey 12.2.1 works natively without any patches. You just need to either move Monterey from supported Mac or install it via any patcher, then you can reset NVRAM, click EFI boot icon from macOS Monterey-micropatcher USB stick to set proper NVRAM variables needed for Big Sur/Monterey and you have 100% native Mac.

RX6800 supports macOS Big Sur 11.4 or later and macOS Monterey 12.0.1 or later. RX6600 supports macOS Monterey 12.1 or later. You will be still able to boot to older macOS versions like High Sierra/Mojave/Catalina, but without acceleration as there is no driver support in these.

Both supports Windows 10/11 in legacy/UEFI mode (also Windows 8.1 is supported with Windows 7 driver, but not recommended). Resume/suspend works both in legacy and UEFI mode!

Cards works using internal power, no SATA power, Pixlas mod or external PSU is needed. RX6800 uses 2x 8-pin power, RX6600XT uses a single 8-pin power.

Real TDP of RX6800 is about 220W well within Mac Pro safety limits. Idle TDP is just 7W. RX6600XT takes just 160W under load and just 3W when idle!

Supports HDMI/DisplayPort Audio out of the box both under macOS and Windows.

RX6800 seems to be a solid 4K performer for DX12 gaming under Windows. RX 6600XT scores half of score but still offering a smooth gameplay. Tested using Shadow Of The Tomb Raider in 4K resolution with ultra details.

These cards are exclusively offered by MacVidCards Europe, but shipping worldwide.

RX6800 benchmarks:

3DMark Time Spy (12 767 points): https://www.3dmark.com/3dm/74499831

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rx6800.gif


tomb_rx6800.jpg


RX6600 benchmarks:

3DMark Time Spy (8857 points): https://www.3dmark.com/3dm/74502253

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rx6600xt.gif


tomb_rx6600xt.jpg
 
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joevt

macrumors 604
Jun 21, 2012
6,979
4,267
If I wanted a RX 6600 /6800 / 6900 with EFI boot screen, I would maybe take @Syncretic's EFI image #887 (contains the GOP driver) and append it after a small EFI image that loads the GOP and adds a UGA on GOP driver.
 

avro707

macrumors 68020
Dec 13, 2010
2,278
1,679
Cards works using internal power, no SATA power, Pixlas mod or external PSU is needed. RX6800 uses 2x 8-pin power, RX6600XT uses a single 8-pin power.


So does that mean that you are using similar connections to an RX580 for instance without needing the Pixlas mod, just to clarify? If so that makes it very easy for upgrades for those who don't want to be stuck to older cards or have to jump to 7,1.
 

MediaGary

macrumors member
May 30, 2022
39
23
I had both a PowerColor 5700 XT [6pin+8pin] and a Sapphire RX 580 [single 8pin] in my 5,1. I now have an RX6800 (non-XT) which uses [8pin+8pin] in my 5,1. I've only used the mini-6pin to whatever the card required. No Pixlas mod.
 
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Spacedust

macrumors 65816
Original poster
May 24, 2009
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Do you know if those cards we are able to drive the latest Apple screens at full resolution?
Not tested yet as these are super expensive.
So does that mean that you are using similar connections to an RX580 for instance without needing the Pixlas mod, just to clarify? If so that makes it very easy for upgrades for those who don't want to be stuck to older cards or have to jump to 7,1.
Yes, RX6800 works perfectly using standard power cables (2x8-pin or 2x6-pin + simple single 6-pin to 8-pin power adapters) as the real TDP is around 215W.

RX6800XT and RX6900XT needs SATA power or Pixlas mod: https://www.macvidcards.eu/installa...nector-for-cards-with-8-8-pin-power-connector
 
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startergo

macrumors 603
Sep 20, 2018
5,023
2,283
Theoretical power limit of the 2x 6 mini connectors is 150W, but I believe shutdown protection occurs at more than 135W consumption. I don't think that a pcie card can consume more than 40 watt from the pcie slot. I would not rely on SATA connection for more than 45W either. All that said I would recommend a Pixla's mod for any power consumption more than 225w constant power draw( remember there are peak moments where more than 225W will be consed).
 
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SDAVE

macrumors 68040
Jun 16, 2007
3,578
601
Nowhere
If I wanted a RX 6600 /6800 / 6900 with EFI boot screen, I would maybe take @Syncretic's EFI image #887 (contains the GOP driver) and append it after a small EFI image that loads the GOP and adds a UGA on GOP driver.
I can see the EFI boot screen with a AMD OEM 6900XT with the 580X MPX module removed. But I have to use a wired keyboard, Bluetooth magic keyboard doesnt work
 

nanaandbump

macrumors newbie
Apr 24, 2018
9
3
Does this mean that any 6600 XT will work natively on the cmp 5,1 running Monterey without any patching? (Provided the proper steps are followed of course). Or does it mean exclusively those cards purchased from MacVidCards Europe? I was under the impression that the cards sold by those guys are simply cards that they have patched/modified to work with the cmp, and thus I am thoroughly confused by the op. . .

The MacVidCards Europe guys don't have the card I want in stock anymore. That and they charge a significant premium over a stock card. I would love to be able to do the patch outlined by Syncretic that fixes the boot sequence issue, but I don't have access to a PC required to do so. I keep seeing posts around the webs mentioning native compatibility, but they don't go into much detail. I'm hoping there is now a solution that doesn't require a PC. If someone could clarify, I would much appreciate it!

Quick rig info:
CMP 4,1 flashed to 5,1
Firmware 144.0.0.0.0
2x Xeon X5680
 

nanaandbump

macrumors newbie
Apr 24, 2018
9
3
Thanks guys, that is what I thought. I was just confused by this post I suppose.
The card I'm looking for is a 6600 XT. It looks like I've found a friend that will let me use his PC to do the flash, so all is well. Thanks again
 
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