GPU Madness in the Mac Pro 5,1: Early 2021 Edition

This is a bit of a throwback to my article from May of last year – Tri-Booting a Mac Pro 2,1 – not long before I had just procured my Mac Pro 5,1 (well technically a 4,1 that was flashed to a 5,1 with dual Intel Xeon 5680 CPUs with 12 cores at 3.33 GHz).  That May 2020 article in itself was a bit of GPU madness with me employing 3 different cards for various purposes.  The GPU madness this year is a bit of a different story, but at the end of the day comes down to the same conclusion for my use case but with just 2 of those 3 cards being used.

This 5,1 is a very powerful machine and has been an incredible pleasure to own so far (grabbed for under $1000 shipped on eBay last year).  As fate would have it, I had been quite satisfied with the performance I was getting from the GTX 980Ti in my 2,1 last year and got another.  While I was fully aware of the limits of the NVidia web drivers last year (High Sierra was the end of the line), these 980/980Ti cards and their successors – the 1080 and 1080Ti are great options for the Mac Pro 5,1 running High Sierra with the NVidia Web Drivers.  It is a shame you can’t really push these cards any further.

The only trouble is that with the NVidia cards running Web Drivers, if power is interrupted or if you ever need to reset the PRAM, the default goes back to the Mac Default driver, giving you a dark screen and no video when booting your Mac back up.  The fail-safe is to always have a backup low powered video card running “in tandem” in another slot that can produce a boot screen or boot natively with no special drivers.  NVidia Maxwell and Pascal cards (like the 980Ti and 1080Ti) unfortunately require these special web drivers (Kepler cards like the Titan Black 6 GB or GTX 780Ti however have native MacOS drivers and do not require dedicated web drivers). 

In my case (and in the case of many others) just like I discussed in last year’s article, a great option for that secondary video card is the Radeon HD 2600 XT.  Why this card in particular though?? What’s so special about it? This card not only provides you a boot screen, but also provides you with the ability to boot into Snow Leopard and get full 3D acceleration (yes it’s a weak card – even for Snow Leopard overall, but it’s better than no 3D acceleration at all and gets you up and running when you need it to).  What’s more is that it only takes up a single slot.  No overhang – no large fan or heat sink sticking out preventing you from installing other cards.. it’s just a single slot wide.  It also requires no additional auxiliary power and will work in all versions of the cMP (Classic Mac Pro) from the 2006 1,1 to the 2012 version of the 5,1.

These requirements were all especially important to me after recently upgrading to NVMe Storage (more on that in another article).  With my GTX 980Ti in Slot 1 (lower slot) at 16x, my recently acquired PCIe NVMe RAID card (WD AN1500 1 TB) in slot 2 (capped at 8x in the 16x slot) and my flashed GC Titan Ridge in slot 4 (rated at 4x in that 4x slot), all that I had left was slot 3 for a GPU that produces a boot screen and it had to be single wide.  Despite the fact that slot 3 is just 4x, that’s more than enough bandwidth for this low rated card, which is only going to be used to push 1080p 60Hz anyway and mainly just be used for boot screens, so PCIe v2 at 4x was plenty for that card.

The Metal Conundrum with NVidia and AMD

Let’s say you aren’t going to use a Titan Ridge, and you don’t care about NVMe storage and don’t care about Snow Leopard but want to run your 980Ti or 1080Ti for Windows 10 and High Sierra and you also want to run Mojave and Catalina using a supported card.  You could technically put something like an ITX RX 560 4 GB in Slot 2 which is low powered as well (if you just needed a display card for Mojave/Catalina), but not so fast.. at least in High Sierra for sure.  When you boot High Sierra with the NVidia Web Drivers for a Maxwell or Pascal NVidia card and you have an AMD metal card present, a driver clash occurs and since you have no boot screen, you’re now stuck.  You’ll get to the login screen but can go no further.  You then have to zap the PRAM and only use the RX 560, so at that point it becomes a useless exercise to try running High Sierra with the NVidia Web Drivers and a low powered AMD Metal card like the RX 560 also installed.  So if you configure a Mac Pro 5,1 with a 980Ti/1080Ti and RX 560, you might as well just not even bother counting on using the higher powered cards in MacOS at all (at least High Sierra), which is a real bummer.

Note: If you go to Mojave or later (without OpenCore), say goodbye to Snow Leopard

Be aware that the minute you boot into Mojave or later (and you are not using OpenCore), if you have a non-Metal EFI card installed like the AMD HD 2600 XT, you’ll get an error and won’t be able to boot into the OS at all.  I have not tried running my PC (non-flashed, non-EFI) Radeon 5670 simultaneously yet, so it may be an option for 3D acceleration with OpenCore running and may not trigger the clash.

Why not just use a Radeon RX 580 or 5700 XT and call it a Day?

This is a tricky one, but it’s only tricky for if you’re a gamer.  If you’re using your Mac Pro 5,1 for gaming as well like I do in Windows 10, the 980Ti is still significantly faster than the RX 580 while the 1080Ti literally smokes the RX 580, so both NVidia cards provide a ton of bang for the buck and are far more powerful for gaming and FPS than the RX 580.

Courtesy of the GPU Gaming Score Aggregator, UserBenchmark, see the scores accordingly:

NVidia GTX 980Ti vs AMD RX 580

NVidia GTX 1080Ti vs AMD RX 580

Like anything though there are two sides to the story.. If gaming is not important to you at all and you are only using your Mac with MacOS, the RX 580 is actually the better overall value for the 5,1 due to the Metal performance (it’s much better for Metal intensive apps than the 980Ti and even slightly better than the 1080Ti.  Check out the Geekbench Metal Results Browser for those GPUs:

Radeon RX 580: 44803

Geforce 1080Ti: 43386

Geforce 980Ti: 26765

As for the Radeon 5700 XT.. it wins versus the 980Ti for gaming, but loses to the 1080Ti.  It wins versus both on Metal scores, but surprisingly Metal performance is not a major leap over the RX 580.

5700 XT Gaming comparison (again from UserBenchmark):

NVidia GTX 980Ti vs AMD Radeon 5700 XT

NVidia GTX 1080Ti vs AMD Radeon 5700 XT

Metal performance came out to 49803, giving you a good 10% speed boost over the RX 580 for Metal intensive work like video encoding in the current releases of iMovie/FCPX, etc. 

The 5700 XT requires Catalina to run stable (simple patch for the 5,1 with the dosdude1 patch since Mojave was the last official version for the Mac Pro 5,1 or you can use OpenCore and even get boot screens).  The 5700 XT is simply prohibitive from a cost standpoint though and is why I would not recommend it right now (see “The Final Verdict” below):

The Final Verdict

The problem in all of this is that we’re still in the world of the pandemic where people are still playing it safe and riding it out staying at home for the most part.  Lots of new people have gotten into PC gaming this year and last year and the same thing has happened with crypto-currency mining (all these indoor hobbies have simply blown up).  Couple that with greedy eBay bot scalpers and a global shortage on semi-conductors and you have a real mess on your hands for the GPU market, so what’s the best value overall right now? 

If you’re a gamer, I’m going to stand by my continued assessment of the GTX 980Ti or 1080Ti and a Radeon HD 2600 boot card to have as a backup for boot screens in case of issues with the NVidia Web Drivers (be patient on the HD 2600 – some sellers want over $100 and some $150 for these relics.. they’re worth $50 to $60 – don’t pay much more than that unless you are desperate).  You won’t be able to run Mojave or later for now in that tandem setup for MacOS (again due to the web driver limitations), but High Sierra has a little bit of life left and will likely get you by until the prices come down, plus you’ll be very happy with the performance of the 980Ti and 1080Ti for Windows 10 gaming.  People are lauding the RTX 3k series and 2k series for the Ray Tracing and the fact that they are better crypto mining cards, so you are seeing the market saturated with 980/980Ti and 1080/1080Ti cards right now – all great for gaming and VR and good to excellent Metal performance.  While they too are slightly elevated in price (980Ti was going for $200-$250 last year and is currently trending $350 to $400 while the 1080Ti was trending $500 or so last year and has not changed much).

If you’re not a gaming enthusiast, the RX 580 is the way to go.  It will run Mojave and later and offers plenty of power.  Even in today’s elevated eBay market, you can find these cards for around $300-$400 on average if you look around (sadly they were under $200 last year).

What about that AMD Radeon 5700 XT? It seemed like a winner.. Best Metal score versus the RX 580, GTX 980Ti and 1080Ti and better gaming scores than the 980Ti.  The problem is that this card was retailing for $400 to $500 last year on average.  It now retails for $649 (for the PowerColor Red Devil variant) and is trending for $1000 to $1500 right now on eBay for all variants.. that’s an insulting double the retail price! Thanks a lot scalpers.  The value just isn’t there on the 5700 XT right now and for the premiums the standard 5700, 5600 XT and 5500 XT are going for (all $100s over retail), it just not a great idea to move to a Navi card unless you absolutely must run Catalina and later on your 5,1.

As a last note, I should also mention the Vega 56 – an overlooked card.  Equal to about the 980Ti for gaming, but scores over 64,000 on Metal and falls within TDP for the Mac Pro 5,1.  It’s probably worth looking at and most have been passing it over for the Navi cards like the 5700 XT.  It will also run Mojave giving you 32-bit App Support.


Good luck on your GPU hunt during this time of March (GPU) madness!