[SOLVED] AMD GPU for i7-980/Xeon X5680 (stock)

imrazor

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I recently picked up a system for use as a living room computer. It happens to be a Mac Pro that's rather long in the tooth. It's a single CPU model, featuring a Xeon X5680 which is functionally identical to an i7-980. The video card will need to fulfill two requirements: 1) it has to be an AMD card (MacOS doesn't like modern Nvidia GPUs) and 2) it can't require more than 2 x 6-pin PCIe power connectors. The other thing I'd like to avoid is getting something like a Radeon 5700 XT which would surely be bottlenecked by this old CPU.

I will be dual booting and using Windows to run games, not just Mac games. Though the processor is old, it is a 6-core hyperthreaded CPU at 3.3 GHz so it should be able to handle moderately demanding games. AFAIK, the Mac Pro cannot be overclocked, so that's not really an option.

EDIT: Budget is ... cheap as possible. $150 - $200 is what I'm thinking. I'm open to used or new parts.
 

Lutfij

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Apart from the specs on your Mac Pro, I'd be very concerned about the effective amount of power that PSU can deliver for the entire system with a discrete GPU populating the system. In fact every AMD GPU you're going to be looking at will be power hungry and I'm sure the Mac Pro you have has a proprietary connector for the PSU not to mention a propreitary form factor for the PSU.

I stand to be corrected which is why I'd like you to include the model for the Mac Pro and if possible the age of the system's PSU.

Are you sure you can't work with Nvidia cards? If you look through builds featuring Hackintosh's you'll see Nvidia GPU's getting favor.
 
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boju

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Probably Rx 570 using 6pin to 8pin adapter. 5700XT has a 6 & 8pin. Difficult to find a card having two 6 pins for more performance, most either have an 8, 6+8 or 8+8.

Rx 570 psu req 450w.

Next, Rx 560. 1x6pin, bit slower than the Gtx 1050Ti.
 

Lutfij

Titan
Moderator
Apart from the specs on your Mac Pro, I'd be very concerned about the effective amount of power that PSU can deliver for the entire system with a discrete GPU populating the system. In fact every AMD GPU you're going to be looking at will be power hungry and I'm sure the Mac Pro you have has a proprietary connector for the PSU not to mention a propreitary form factor for the PSU.

I stand to be corrected which is why I'd like you to include the model for the Mac Pro and if possible the age of the system's PSU.

Are you sure you can't work with Nvidia cards? If you look through builds featuring Hackintosh's you'll see Nvidia GPU's getting favor.
 
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imrazor

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@boju I do have a 2x6-pin to 1x8-pin adapter I can use if necessary. The PCIe power connectors do not connect to the PSU, like a PC, but rather connect to two 6-pin "mini PCIe" power connectors on the motherboard.

@Lutfij The Mac Pro (referred to as a "2010" or "MacPro5,1" model) came with an ATI Radeon 5870, which has a power draw of ~190w. It should be able to handle at least a modern mid-range GPU. Here's the PSU, which is rated at 980 watts:

http://www.macpartsonline.com/661-5449-apple-power-supply-980-watts-for-mac-pro-2012-2010-2009-a1289.html

Recent Nvidia cards (Maxwell, Pascal) do not work with OS 10.14 due to a driver dispute with Apple. Nvidia has been releasing web drivers for older versions of MacOS, but 10.14 uses a new driver architecture and API ("Metal") that Apple is not sharing with Nvidia.

I currently have a GTX 670 plugged into the Mac Pro, which works, but performance is mediocre. I also have a 1050Ti which I cannot use thanks to Apple and Nvidia's dispute.
 

stonecarver

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I'm not sure so much the needs making the Mac drivers side work but I'm playing around with same set up non Mac with the 1366 motherboard Xeon 5670 , AMD RX 580 8gb and I did have to use one 6 to 8 pin PCI-e adapter. Sometimes RX 580's come up $110.00 to 200 ebay. And ya don't know what mac has for a power supply .

One more thing I was testing with latest Hitman 2 . and Shadow of the Tomb Raider and buttery smooth.
 
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stonecarver

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One thing to check before you leap to the RX 500's is your mac UEFI bios. My 1366 has UEFI so my RX 580 works. If your mac does not RX 470 /480's still work with older BIOS. I think Macs did the UEFI before windows side of the computer race but wanted to put that out there. Happy duel booting.
 
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imrazor

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I know it's been quite a while since I first posted this, but I wanted to share my final solution. There are some PSU hacks out there that involve 'tapping' the PSU power lines and adding 8-pin connectors. Not being much of a hardware modder, I decided to forego this option.

Instead I found that reference models of the Vega 56 feature two BIOSes on board, a performance BIOS and a low-power BIOS. The low power BIOS only draws 150 watts of power, which is exactly the maximum that the Mac Pro can deliver. So I got an MSI "Air Boost" Vega 56, based on the reference PCB, and put the BIOS in low power mode. However, the card still wanted two 8-pin connectors. I solved that issue with an EVGA Powerlink. See here: https://www.evga.com/articles/01051/evga-powerlink/

This allowed me to plug the two standard 6 pin connectors into the Powerlink, and then insert the device into the two 8-pin connectors on the card. It's been working great ever since.

P.S. Nvidia isn't a great choice for Macs right now. Nvidia is no longer providing drivers for recent OS versions, so you'd have to run an ancient version of OS X to get hardware acceleration.
 

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