iMac Pro iMac Pro Vega 56 vs 64 Gaming Performance?

Discussion in 'iMac' started by seasurfer, Feb 22, 2018.

  1. seasurfer macrumors 6502a

    Dec 12, 2007
    I am just so tempted get this with the Micro Center $1000 discount.

    I like to know if there is a difference between the 56 and 64 when it comes to gaming. Anyone has any insight?
  2. casperes1996 macrumors 68040


    Jan 26, 2014
    Horsens, Denmark
    Of course there is a difference. Is it big enough to pay $1600 extra? Hell no.

    56 and 64 refers to the CUs in the GPUs. (CU = Compute Unit). If we assume identical clock speeds and no VRAM bottlenecks, the 64 will be about 12% faster overall. (14.2% but I reduced it a bit since I wanted to account for encore components that don't scale with CUs)
  3. jwpoof macrumors member

    Jan 11, 2006
    My question is, that's the speed difference. But how much does the additional VRAM impact FCPX usage? Reports are that FCPX will eat all the VRAM available. Anecdotally, the reports are that 64 is noticeably better in that regard. I'm sorry to intrude, but I'm throwing that out there if anybody has any thoughts, because my trash can is showing its age and I'm tempted to pick up a micro center special until the new Mac Pro materializes.
  4. JVNeumann macrumors member

    Mar 23, 2017
    From a gaming perspective, the desktop* version of the Vega 56 comes in just above the GTX 1070, but the Vega 64 is a bit below the GTX 1080. Given the price difference between the 1070-1080 is only a few hundred (crypto-mining inflation notwithstanding), it would indeed be ridiculous to pay much more to go from a 56 to a 64, when the jump is roughly half the size of Nvidia's competing cards. In other words, paying more than ~$250 to upgrade to a 64 for gaming is definitely not money well spent.

    Although I'm told Vega is slightly better at 4k+, so maybe in an iMac it's a bit closer to a 1080 than in regular HD. But I doubt it'd make a noticeable difference.

    *Is the iMP version under-clocked?
  5. casperes1996 macrumors 68040


    Jan 26, 2014
    Horsens, Denmark
    I mean, how much VRAM you need entirely depend on the complexity of the content. There's no real benefit to having much more than you need. I'd personally say both GPUs have sufficient VRAM. But if you layer complex 3D scenes, maybe not.

    AMD GPUs in general do better at higher resolutions. And it doesn't stop at 4k. If you super sample up to 8k AMD wins even more. Difference between DirectX and Metal (testes in HITMAN) also decreases at higher resolutions
  6. jwpoof macrumors member

    Jan 11, 2006
    Thanks for your response. I use a lot of plugins and layers. Not much 3d but I can make a D700 Mac Pro slow to a crawl. The BareFeats benchmarks indicated as much as a 30% improvement between the 56 & 64 with tests like BruceX. If there were no microcenter discount, I'd happily buy the 64 10 core, but it sounds like I'd be fine in the interim with the base model.

  7. casperes1996 macrumors 68040


    Jan 26, 2014
    Horsens, Denmark

    I would assume that difference is in part because the 64 might be clocked higher too and in part because of the nature of the benchmark. BruceX is more heavily layered than any real work you might think of doing for a timeline of that size I should think.

    I mean. Looking at apples price difference I’d go for the 64 if I was buying one. But with how much extra I’d have to pay with the discount it’s juse not worth it I think. My 4GB R9 M295X generally does well enough for me for now. It can be slow at times but overall good enough. And there’s 8GB in the 56
  8. anticipate macrumors 6502


    Dec 22, 2013
    This is a great thread because I went back and forth a lot with this. This is a GPU discussion and I am going to talk a lot about RAM and system cores, but it's all important to the GPU discussion because of the way the systems are sold:

    I have both an 8 core 56 base model on my desk (Micro center deal) and now also a 10 core 64 GB Vega 64 (16GB VRAM) model in for testing. (There's a very good $700 off deal at B&H via Apple Insider).

    I sang the praises of the base model when I got it, and not without good reason: it IS fast. Way faster than a maxed out 2017 iMac in many cases. WAY faster than a 4 core MBP. And there are only a relatively few use cases when all those CPU cores light up, even when using FCPX. But they DO light up when doing things like noise reduction, Red RAW playback, CPU heavy codecs etc.

    The Vega 56 chip is only about 15-30% slower (in FCPX, in general) in the iMP. It's not a big jump at all speed wise, especially if you game. But it DOES have 2X the VRAM.. and I think that, combined with the extra cores and slightly higher clock speed - do edge it out over the 56.

    I never, ever thought I would say that. I have to eat my words. (I was thinking of a DESKTOP Vega 56, which is very fast and I tried as an eGPU for a while). The Vega PRO 64 in the iMP is about the speed of a desktop 56. Keep that in mind.

    I run an additional 5K monitor at 5K off the iMP. At first all was well, but then I noticed a few times when editing that I was tapping out the both the system RAM and the VRAM... and I often (usually) ran with a swap file going on the base 32GB model. The swap file use was moderate to light - but it was happening.

    I am not sure if it is because the GPU VRAM was being saturated, and swapping out, or what. However the result was that this seemed in some specific 4K+ editing scenarios to actually slow down the machine - as seen as some stuttering. Although memory "pressure" was low, the system was still chewing through all the RAM and VRAM it had.

    I have since performed some very basic testing on the 10 core model. So far, it is noticeably faster than the base model. Measurably, it's about a 25% bump. I think it's because now I'm not saturating the RAM (main or Video). It's not because of the additional processing power, though of course that helps.

    I thought of adding RAM. It probably would have solved my stutter issues (it did on my old 8 core D700 nMP). But to go from 32 to 64GB is over $1000 at OWC, and you have to send it in. It's a PITA to upgrade. That also doesn't upgrade the GPU, or CPU. In the end I paid $2100 more to upgrade the machine to 64GB, 2 more cores of GPU, and a Vega 64 with double the VRAM. That was a better deal.

    As a result, I will be selling the base iMP model. Luckily because few people live near a Micro Center, I can easily recoup all of what I paid, even selling it with a $500 discount.

    Bottom line - it depends on what you're doing. I suspect without another 5K screen attached, or not performing lots of heavy layered 4K video, that the base model screams. It sure did in some of my tests. But in MY case, for even $4,000 paid - that's a lot of money to have a machine that even occasionally slightly stutters. Seeing as I need this thing to last 3-6 years.. it made sense to pony up now to the 10 core model.

    The base model is very very fast. The 10 core / 64 GB / Vega 64 model, at a $2100 (current) upcharge, is definitely worth the extra $. It's almost a dollar for dollar jump in performance for what you pay.
  9. Ph.D. macrumors 6502

    Jul 8, 2014
    OS-X is designed to keep its ram in use rather than free it up, e.g. in order for stuff to remain in memory for quick access rather than go back to the drive for it again. So, if the memory is in use, but memory pressure is low, well, that's totally normal and not a sign that you are running out. (VRAM might be a different story - not sure about that, or even how to view it.)
  10. jwpoof macrumors member

    Jan 11, 2006
    Thank you very much for this response. You’ve convinced me.
  11. Rockadile macrumors 6502

    Jun 11, 2012
    Vega 56 (Microcenter deal) = gamers & buyers that won't recoup purchase cost using the iMac Pro
    Vega 64 = everyone else

    Use the saving from discount for an eGPU setup in the future.

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