AMD Radeon RDNA2 Navi (RX 6600 XT, RX 6700 XT, RX 6800, 6800 XT, 6900 XT) [2020-10-28, 2021-03-03]

Discussion in 'Architecture and Products' started by BRiT, Oct 28, 2020.

  1. ECH

    ECH
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    There is a piece of this puzzle that we are forgetting...the drivers.
    In 2019 the 5700xt struggles to keep pace with the 2070s in certain games.
    https://i.ibb.co/Bn0myVB/outter-worlds-slow.jpg
    https://i.ibb.co/99CbJcN/jedifallenorder-slow.jpg
    https://i.ibb.co/vJTKwrq/gears-5-slow.jpg


    I didn't see improvements to the 5700xt until early this year, 2020. 5-6 months after release and after their December mega driver release. And, it was on newer titles that the 5700xt was matching or beating a 2070s. No fanfare. No ticker-tate parade.

    https://i.ibb.co/Bqt9hjc/sws1440p.jpg
    https://i.ibb.co/JzYNRkB/HD0.jpg
    https://i.ibb.co/KbjdhrF/Gears-5.jpg
    https://i.ibb.co/Zz056G1/F1-2020.jpg
    https://i.ibb.co/XF7ZJdX/death-stranding.jpg

    The only game that seems to struggle for 5700xt is Watch Dogs: Legions. However, per the dev's own release notes, today, they optimized for the RX 30 series (a bit sus. IMO). And still people are reporting problems with that game. So, I treat it as a one off until it's finally optimized for RX series.

    Lets not forget:
    5700xt: 40 CUs, 64 ROPs, 160TMUs, 2560 Shading Units, 10.3B Transistors @ 225watts with a 251 mm² die size
    2070s : 40 SMs, 64 ROPs, 160TMUs, 2560 Shading Units, 13.6B Transistors @ 215watts with a 545 mm² die size

    The point is that it's very possible that RTG will optimize the performance of the RX 6000 series as times goes on. I can only hope it doesn't take as long as the 5700xt.
     
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  2. MuteyM

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    It's not exclusive to RDNA, it goes back all the way to the first GCN. See the amdgpu_device_resize_fb_bar() function in AMD's Linux kernel mode driver.


    For GPU access to system memory, all modern x86 CPUs have automatic cache coherence via snooping built into their PCIE controllers. You can see in the Vulkan GpuInfo database that any system memory heaps (those without the DEVICE_LOCAL bit) all have the HOST_COHERENT bit set, meaning any GPU writes to system memory are automatically coherent with the CPU, no matter whether caching is enabled or not.

    Going the other way, CPU access to GPU memory on AMD GPUs is always considered coherent, but not automatically in hardware. Instead it's because the kernel mode driver explicitly flushes/invalidates the GPU's "host data path" caches every time a command buffer is submitted from user space. Thus to user-space drivers like Vulkan/DX12 it appears that anything they wrote to GPU memory gets seen by the GPU automatically when the command buffers execute.

    I guess AMD in only making a big deal about it now because resizable BARs require BIOS / motherboard / OS support that's fairly recent, and PCIE 4.0 finally has high enough bandwidth that direct CPU access to GPU memory is starting to make sense for more use cases.
     
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  3. PSman1700

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    The 23+ Tf 6900xt looks promising.
     
  4. Kaotik

    Kaotik Drunk Member
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    This is dishonest comparison. 2070S is heavily cut down chip, 5700 XT isn't. Those transistors are for the full chip.
     
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  5. ECH

    ECH
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    Then you can take it up with:
    https://www.techpowerup.com/gpu-specs/geforce-rtx-2070-super.c3440
    https://www.anandtech.com/show/14586/geforce-rtx-2070-super-rtx-2060-super-review
    https://www.guru3d.com/articles-pages/geforce-rtx-2060-and-2070-super-review,4.html
    etc, etc where I obtained the information. But to be honest, I seriously doubt anyone is trying to be "dishonest".
    :-D
     
  6. trinibwoy

    trinibwoy Meh
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    That was an impressive exercise in cherry picking. My recollection is that the 5700xt was pretty competitive with the 2070 super when the latter first launched.
     
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  7. Scott_Arm

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    Let's say average clock of the 3090 is 1900 MHz. It has 112 rops so that's 213 GPixels/s
    Let's say the average game clock of a RX 6800 is 1815. It has 96 rops so that's 174 GPixels/s

    Pretty interesting. Means it's not a fillrate advantage or a a compute advantage. Shouldn't be texture sampling either. Definitely not bandwidth. 3090 should even have a geometry advantage. I wonder if the difference is a straight up power limit in some way. Wonder if a 3090 undervolted with roughly the same clocks would actually perform better. I am very curious. Does SAM actually a dress a significant bottleneck that gone under the radar? Or are some of these games very cache friendly in some way, where the infinity cache leads to big gains.
     
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  8. xEx

    xEx
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    We will see in a month. maybe be drivers, or settings or another 10 diff reasons.


    upload_2020-10-30_19-4-8.png



    No reviews? If true this doesn't look good at all...
     
  9. Scott_Arm

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    Lol no one could miss the sarcasm in that post. I'm really curious to see 3rd party benchmarks.
     
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  10. xEx

    xEx
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    Well now I'm really doubting AMD's numbers. This is only done when you want to hide ur performance rather than showing it..

    Looks like now we know why we didn't have an NDA date.
     
  11. tsa1

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    I'd actually say AMD is very confident in the launch if they decided to publish such extensive bench results now without starting pre-orders and the other stuff... They'd get shredded if something is way too off when someone tries to replicate their numbers two weeks later.
     
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  12. Subtlesnake

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  13. pharma

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    Reviews should be good. I wonder if default clocks were used on the latest benchmarks or if there were any overclocks.
     
  14. techuse

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    Why not? Some games a Vega 64 can match or beat a 1080ti.
     
  15. majord

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    Main thing I'm curious for from 3rd party reviews is frame times , minimums.

    RT I don't think we're going to get anything too meaningful until we see games developed in future , targeting both , I.e not under RTX SDK or whatever . Are any of the existing implementations even compatible?
     
  16. xEx

    xEx
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    Context. This was Steve actually complaining of AMD showing the bench themselves.
     
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  17. trinibwoy

    trinibwoy Meh
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    What's wrong with AMD showing numbers? Isn't that normal.
     
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  18. eastmen

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  19. Rootax

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    On paper their all DXR games, they should run on rdna2.
     
  20. xEx

    xEx
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    Well asked him. I suppose is because AMD showed too many benchs.
     
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