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-   -   RDNA2 / Big Navi (https://www.mersenneforum.org/showthread.php?t=26134)

M344587487 2020-10-28 16:59

RDNA2 / Big Navi
 
AMD announcement: [URL]https://www.youtube.com/watch?v=oHpgu-cTjyM[/URL]


[url]https://www.youtube.com/watch?v=haAPtu06eYI[/url]



tl;dr:
[LIST][*]Infinity cache - "Graphics optimised, high density, high speed cache, based on the Zen L3 cache". graph shows 2.17x bandwidth of infinity cache + 256 bit GDDR6 compared to 384 bit GDDR6 on typical gaming workloads[*]Smart access memory - Zen3 processors can have full access to GPU memory? Showing single digit % performance increase in some games not specifically optimised for it, promises that workloads can specifically optimise for even better performance. Performance figures shown are with this feature enabled so this is one way they've fudged the numbers[/LIST] 6800
[LIST][*]60 CU's[*]1815 MHz game clock[*]2105 MHz boost clock[*]128MB infinity cache[*]16GB GDDR6, 256 bit?[*]250W TBP[*]November 18th[*]$579[/LIST] 6800XT
[LIST][*]72 CU's[*]2015 MHz game clock[*]2250 MHz boost clock[*]128MB infinity cache[*]16GB GDDR6 256 bit[*]300W TBP[*]November 18th[*]$649[*]Shown rivalling 3080 in games[/LIST] 6900XT
[LIST][*]80 CU's[*]2015 MHz game clock[*]2250 MHz boost clock[*]128MB infinity cache[*]16GB GDDR6 256 bit?[*]300W TBP[*]December 8th[*]$999[*]Shown rivalling 3090 in games[/LIST] At a glance it looks promising. Infinity cache has a chance of being insanely good for our purposes but who knows. The high price is also a good sign that they're confident that they're competitive, in gaming. Timely compute and Linux support, unlikely.

firejuggler 2020-10-28 18:05

The 6800 look like a fair competition to the RTX3070 price wise. Now we need more numbers... like FP 64 performance. For our "need".


edit: ok I found it :

[code]
FP64 (double) performance 1,010 GFLOPS (1:16)[/code]
Around 3 time the performance or a rtx 3070 (in FP64)
[url]https://www.techpowerup.com/gpu-specs/radeon-rx-6800.c3713[/url]

Mark Rose 2020-10-28 21:20

Still nowhere near the 3.5 TFL64OPS of the Radeon VII, sadly.

I do wonder how the Navi 10 mining GPU that showed up in recent kernel patches will do. It's Navi 10 though, so probably the same 1/16 FP64 performance.

mackerel 2020-10-28 22:22

The cache is the biggest "new" variable I guess. Be really interesting to see how that works out in non-gaming uses.

I think the 6800 will be positioned above 3070, if you compare their relative performance compared to the 3080 and 6800XT respectively.

moebius 2020-10-28 23:18

[QUOTE=Mark Rose;561376]Still nowhere near the 3.5 TFL64OPS of the Radeon VII, sadly.[/QUOTE]
Even a Vega 64 still has 0.792 Tflops at FP64. Maybe the fast HBM2 memory is missing.

M344587487 2020-10-29 00:37

[QUOTE=Mark Rose;561376]Still nowhere near the 3.5 TFL64OPS of the Radeon VII, sadly.[/QUOTE]Unfortunately that was never on the cards, Navi has always been about optimising for graphics performance over all else. Good DP is now the realm of CDNA2 and there's a 99% chance that CDNA2 is not the price-performance we're looking for.

[QUOTE=Mark Rose;561376]I do wonder how the Navi 10 mining GPU that showed up in recent kernel patches will do. It's Navi 10 though, so probably the same 1/16 FP64 performance.[/QUOTE]Wild guess, it's the exact same as an existing card just with all the extraneous features removed and maybe a bios tuned for efficiency. It could just be a ploy to redefine and push Navi 1 as a mining generation. Navi 2 seems to be of less interest to miners as Ethereum and Monero both require random access to a 2GB file so the infinity cache is scuppered, and the raw bandwidth of Navi 2 is not much higher than Navi 1. It's been a while but last I paid attention these two (and derivatives thereof being pedantic) accounted for the vast majority of GPU mining.

preda 2020-10-29 01:43

[QUOTE=M344587487;561339]Timely compute and Linux support, unlikely.[/QUOTE]

Yep, unfortunately: the hardware is done, time to start work on the software side..
(and by that I don't mean *our* software side, I mean AMD's software side)

axn 2020-10-29 02:05

[QUOTE=Mark Rose;561376]Still nowhere near the 3.5 TFL64OPS of the Radeon VII, sadly.[/QUOTE]

This might matter less than you think, to wit...

[QUOTE=mackerel;561382]The cache is the biggest "new" variable I guess. Be really interesting to see how that works out in non-gaming uses.[/QUOTE]

The 128MB cache is big enough to fit our current FFTs in their entirety. This could indeed be very interesting.

tServo 2020-10-29 12:43

[QUOTE=axn;561412]This might matter less than you think, to wit...



The 128MB cache is big enough to fit our current FFTs in their entirety. This could indeed be very interesting.[/QUOTE]

It probably depends on whether that cache is able to be manipulated and configured directly by the programmer or if management of it is left to some inflexible on chip algorithm.

Mark Rose 2020-11-09 15:47

[url=https://videocardz.com/newz/amd-radeon-rx-6800-allegedly-1-5x-faster-than-geforce-rtx-3090-in-cryptocurrency-mining]AMD Radeon RX 6800 1.5x faster than GeForce RTX 3090 in mining[/url]

If true, it's going to be fun finding one. I don't think it will have higher FP32 performance than the RTX 3xxx, but this bodes well for INT performance. Could be TF monster.

Mark Rose 2020-11-11 19:23

So the above rumour was a bust, but now there are some benchmarks: [url]https://videocardz.com/newz/amd-radeon-rx-6800-xt-and-rx-6800-geekbench-opencl-benchmarks-leaked[/url]


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