Discussion RDNA4 + CDNA3 Architectures Thread

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DisEnchantment

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Mar 3, 2017
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With the GFX940 patches in full swing since first week of March, it is looking like MI300 is not far in the distant future!
Usually AMD takes around 3Qs to get the support in LLVM and amdgpu. Lately, since RDNA2 the window they push to add support for new devices is much reduced to prevent leaks.
But looking at the flurry of code in LLVM, it is a lot of commits. Maybe because US Govt is starting to prepare the SW environment for El Capitan (Maybe to avoid slow bring up situation like Frontier for example)

See here for the GFX940 specific commits
Or Phoronix

There is a lot more if you know whom to follow in LLVM review chains (before getting merged to github), but I am not going to link AMD employees.

I am starting to think MI300 will launch around the same time like Hopper probably only a couple of months later!
Although I believe Hopper had problems not having a host CPU capable of doing PCIe 5 in the very near future therefore it might have gotten pushed back a bit until SPR and Genoa arrives later in 2022.
If PVC slips again I believe MI300 could launch before it :grimacing:

This is nuts, MI100/200/300 cadence is impressive.

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Previous thread on CDNA2 and RDNA3 here

 
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Ghostsonplanets

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Mar 1, 2024
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50 TFLOPs for a 32 WGP design with board power of 215W is a quite solid PPW improvement over the 7900 XT. Really showing off RDNA 4 impressive PPA improvements over RDNA 3, as AMD is greatly reducing area and power usage while exhibiting same performance as a bigger RDNA 3 card. Definitely feels like we're bound for another RDNA 2 generation of greats cards. Shame that only two dies remained though.

I now wonder what will be the board power of Navi 44. N44 is basically half of N48 and will probably clock a bit lower too. Maybe something like 100W board power? Regardless, AMD has good designs for both DIY and also to be slotted into Gaming Laptops alongside Strix Halo.
 

Timorous

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The Navi 48 samples are capable of 50 TFLOPS on a ~215W board.

So 3.05 Ghz then which is not bad at 215W board power.

Performance of 64CUs at 3Ghz with enough memory bandwidth should be in the ballpark of an OC'd 7900GRE and on the heels of the 7900XT. Maybe more if there is an IPC improvement or the sustained clock in games is a bit higher.

Suspect N44 will clock higher and target 120-130W something like that. Should be good for 25-30 Tflops which will be a bit below the 7700XT unless there is an IPC improvement as well.
 

CouncilorIrissa

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Jul 28, 2023
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So 3.05 Ghz then which is not bad at 215W board power.

Performance of 64CUs at 3Ghz with enough memory bandwidth should be in the ballpark of an OC'd 7900GRE and on the heels of the 7900XT. Maybe more if there is an IPC improvement or the sustained clock in games is a bit higher.

Suspect N44 will clock higher and target 120-130W something like that. Should be good for 25-30 Tflops which will be a bit below the 7700XT unless there is an IPC improvement as well.
N44 still only has 2/3 of 7700XT's memory bandwidth, so little chance of competing against the 7700XT (unless it's somehow massively less membw hungry)
 

Timorous

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N44 still only has 2/3 of 7700XT's memory bandwidth, so little chance of competing against the 7700XT (unless it's somehow massively less membw hungry)

Agreed which is why I said below the 7700XT. Probably fills the gap between 6700XT and 7700XT so around 4060Ti performance which would not be bad at $330 ish, especially with 16GB of vram.
 

SolidQ

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Jul 13, 2023
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Big problem we don't know how new WGP perfomance compared to RDNA3
at least hope N48 is 2x8pin, not new 12
 
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PJVol

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May 25, 2020
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Of course so any guess is going to have a huge +/-
Like what? Even if they are 1:1, 7900XT RT-less perf. at 215W and $400 looks already competitive with nv next gen. Add 5% to the average from the RT on steroids (BVH lookup) and you'll get somewhere inbetween 7900's xt and xtx for let's say $450-500

at least hope N48 is 2x8pin, not new 12
Wouldn't 8+6 (or even a single 8-pin) be enough?
 
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Timorous

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Like what?

IPC might go down or up. Clock speeds might be higher or lower than any assumptions made. Clock scaling may be totally different from prior gens etc.

Any guess like 'a 64 cu RDNA 4 part with 3Ghz clocks should perform like an OCd 7900 GRE' is full of such assumptions which means it can only ever be at best a rough guide and even that requires the assumptions to be broadly there or there abouts. If something fundamentally changes then it can throw the whole thing out.

An example would be trying to guess 5700XT perf based on specs when using GCN as a baseline, RDNA scales very differently so this kind of speculation would be a mile off.
 

PJVol

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May 25, 2020
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An example would be trying to guess 5700XT perf based on specs when using GCN as a baseline
Or like guessing N31 perf. based on tflops? :)
On a serious note, if this 50tf is not another 01/04 thingy, isn't it reasonable to assume the performance per CU at least hasn't degraded
 

Timorous

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Or like guessing N31 perf. based on tflops? :)
On a serious note, if this 50tf is not another 01/04 thingy, isn't it reasonable to assume the performance per CU at least hasn't degraded

We didn't know the Tflops until launch because we didn't know the clock speeds. Speculation was based on shader count and expected clocks which were both well off due to dual issue and the v/f curve being awful.