Discussion RDNA4 + CDNA3 Architectures Thread

Page 75 - Seeking answers? Join the AnandTech community: where nearly half-a-million members share solutions and discuss the latest tech.

DisEnchantment

Golden Member
Mar 3, 2017
1,747
6,598
136
1655034287489.png
1655034259690.png

1655034485504.png

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.

1655034362046.png

Previous thread on CDNA2 and RDNA3 here

 
Last edited:

Mahboi

Golden Member
Apr 4, 2024
1,033
1,897
96
Are you sure about what you wrote?
RTX 4090: 384-bit paired with 21gbps GDDR6 = 1008 GB/s

Effective BW is Infinity cache hitrate + BW from memory controller.
Nope, not sure. That's why it's a question.
The number just seems very high compared to N44. It's five times more.
I'd be more willing to bet that it's the estimated clocks at 2770Mhz and 2515 Mhz, but the 2 was missed or something.
 

Timorous

Golden Member
Oct 27, 2008
1,748
3,240
136
So the specs look like this for now:
RDNA4SizeSEClocksWGPCUDual-issue ShadersTMUROPsInfinity Cachebus widthGDDR6Effective
BW
Vram
N48~240mm24?32644096 ?256 ?96 ?64MB ?256-bit21.65gbps2770 GB/s16GB
N44~130mm22 ??16322048 ?128 ?64 ?32MB ?128-bit18gbps515 GB/s8-16GB ?
WGP is supposedly new so I don't know what changes that means for the specs.

N44 doesn't look that good for higher resolutions thanks to the underwhelming memory subsystem.

It will be fine at 1080p / 1440p with compromises or upscaling and N48 will be fine for 1440p and 4k with compromises or upscaling.
 

TESKATLIPOKA

Platinum Member
May 1, 2020
2,522
3,037
136
Nope, not sure. That's why it's a question.
The number just seems very high compared to N44. It's five times more.
I'd be more willing to bet that it's the estimated clocks at 2770Mhz and 2515 Mhz, but the 2 was missed or something.
You were too fast. I changed that post of mine, check It out.
I think It's very unlikely he was talking about clockspeed.
 

Mahboi

Golden Member
Apr 4, 2024
1,033
1,897
96
It will be fine at 1080p / 1440p with compromises or upscaling and N48 will be fine for 1440p and 4k with compromises or upscaling.
32 CUs of non-broken RDNA 3/RDNA 3.5 would already probably handle 1440p quite well. The current broken 7600 is already very close. Assuming 20% extra perf, it would honestly surprise me that it can't reach 6700xt or so performance. And with the expected RDNA 4 improvements, maybe it'll be closer to 7700 xt performance...except it has that tiny bus.
Same with 64 CUs of non broken RDNA 3, that would already gain a solid 15% extra, it would put the 7800 xt around 4070 Ti performance? And then RDNA 4 improvements on top of it. I don't think there's going to be a lot of compromises compared to the current top range. Unless you think a 7900 xt is too weak for 4K.
 

Abwx

Lifer
Apr 2, 2011
11,557
4,349
136
So the specs look like this for now:
RDNA4SizeSEClocksWGPCUDual-issue ShadersTMUROPsInfinity Cachebus widthGDDR6Effective
BW

IC BW
Vram
N48~240mm24?32644096 ?256 ?96 ?64MB ?256-bit21.65gbps2770 GB/s16GB
N44~130mm22 ??16322048 ?128 ?64 ?32MB ?128-bit18gbps515 GB/s8-16GB ?
WGP is supposedly new so I don't know what changes that means for the specs.

N44 doesn't look that good for higher resolutions thanks to the underwhelming memory subsystem.

edit: Ok, It's probably just IC BW and not effective BW.
256b bus 693 GB/s and 2770MHz with 64CUs
128b bus 288 GB/s and perhaps 3515MHz along with 32CUs, would be odd that frequency is only 2515MHz for the smaller GPU.
 

TESKATLIPOKA

Platinum Member
May 1, 2020
2,522
3,037
136
32 CUs of non-broken RDNA 3/RDNA 3.5 would already probably handle 1440p quite well. The current broken 7600 is already very close. Assuming 20% extra perf, it would honestly surprise me that it can't reach 6700xt or so performance. And with the expected RDNA 4 improvements, maybe it'll be closer to 7700 xt performance...except it has that tiny bus.
Same with 64 CUs of non broken RDNA 3, that would already gain a solid 15% extra, it would put the 7800 xt around 4070 Ti performance? And then RDNA 4 improvements on top of it. I don't think there's going to be a lot of compromises compared to the current top range. Unless you think a 7900 xt is too weak for 4K.
That depends on what you mean by handle quite well. >60FPS?
average-fps-per-game-2560-1440.png

In raster most likely yes, unless It's a game like City Skylines II. :p
RT is another story.

P.S. I am talking about N44
 
  • Like
Reactions: Tlh97 and Timorous

TESKATLIPOKA

Platinum Member
May 1, 2020
2,522
3,037
136
You confused the GPU frequency with the BW, 2770 is the GPU frequency not the BW.
Same for the other GPU.
If you didn't notice he wrote 2770 for N48 but only 515 for N44.
Unless you want to claim It was a typo and he meant 2515 or 3515, where both are very unlikely for a good reason.
It's not likely for N44 to have lower or much higher clockspeed than N48.
 

Abwx

Lifer
Apr 2, 2011
11,557
4,349
136
If you didn't notice he wrote 2770 for N48 but only 515 for N44.
Unless you want to claim It was a typo I stand with IC BW.
I pointed it in my previous post, the 515 mean either 3515MHz or 2515MHz, the latter seems unexpectedly low, since it s clear that the BW is 288GB/s this number is forcibly related to the GPU frequency.
 

TESKATLIPOKA

Platinum Member
May 1, 2020
2,522
3,037
136
I pointed it in my previous post, the 515 mean either 3515MHz or 2515MHz, the latter seems unexpectedly low.
And precisely for that you are wrong. Look above
On the other hand for IC BW It makes much more sense, which is pretty similar to RDNA3 predecessors.

, the latter seems unexpectedly low, since it s clear that the BW is 288GB/s this number is forcibly related to the GPU frequency.
What forcibly related to GPU frequency? 288GB/s is precisely 128-bit 18gbps GDDR6. It has nothing to do with GPU frequency.
 

Timorous

Golden Member
Oct 27, 2008
1,748
3,240
136
32 CUs of non-broken RDNA 3/RDNA 3.5 would already probably handle 1440p quite well. The current broken 7600 is already very close. Assuming 20% extra perf, it would honestly surprise me that it can't reach 6700xt or so performance. And with the expected RDNA 4 improvements, maybe it'll be closer to 7700 xt performance...except it has that tiny bus.
Same with 64 CUs of non broken RDNA 3, that would already gain a solid 15% extra, it would put the 7800 xt around 4070 Ti performance? And then RDNA 4 improvements on top of it. I don't think there's going to be a lot of compromises compared to the current top range. Unless you think a 7900 xt is too weak for 4K.

7600XT and 7800XT already get + 15% from over clocking to around 3GHZ and a ram speed bump. If N44 and 48 clock closer to 3.3Ghz then N44 should land between 6750XT and 7700XT and N48 would be 7900XT level and that is with no IPC increase.

The XT is a tad weak for 4K ultra imo. it can do 60+ fine in a lot of games but there are also a fair few that fall below 60fps on average so you will need to use upscaling or tune settings to hit 60. Hence N48 with similar performance (and less bandwidth/cache to boot) will also have games where you need to compromise at 4K. If pricing is $600 or less then that is perfectly fine for that price point so not a big deal just how it will be.

N44 will be similar, it would offer 1440p 60 in a lot of titles but there will be a few where you need to turn down settings or use upscaling to hit that FPS figure. Again if pricing is $350 or less that is not really a problem.

So yea, I stand by what I said.
 
  • Like
Reactions: Tlh97 and Joe NYC

Mahboi

Golden Member
Apr 4, 2024
1,033
1,897
96
That depends on what you mean by handle quite well. >60FPS?
average-fps-per-game-2560-1440.png

In raster most likely yes, unless It's a game like City Skylines II. :p
RT is another story.

P.S. I am talking about N44
Yes, that's the numbers from RDNA 3. Which is broken. Hence why I said "non-broken", so you can expect a general flat 15% improvement. And there's RDNA 4's enhancements on top of that.
The XT is a tad weak for 4K ultra imo.
Then we have very different appreciations of weak. I agree with everything else you said, I just don't think 55 or even 50 fps dips in a lot of games really matter.
 

Abwx

Lifer
Apr 2, 2011
11,557
4,349
136
And precisely for that you are wrong. Look above
On the other hand for IC BW It makes much more sense, which is pretty similar to RDNA3 predecessors.

The thing is that he said that the process is N4P, and looking at the perf/watt delta in respect of N5 and N6 this is perfectly in line with the stated frequencies in respect of a 7800XT and a 7600XT, that s exactly what to expect for 4 more CUs in the former case and same CU count for the latter while keeping the same TDPs at worse.
 
Last edited:

Timorous

Golden Member
Oct 27, 2008
1,748
3,240
136
Then we have very different appreciations of weak. I agree with everything else you said, I just don't think 55 or even 50 fps dips in a lot of games really matter.

Several are mid 40's or even lower though and don't even manage 60fps on average.

Alan wake 2, Cp2077, Jedi Survivor, lords of the fallen, last of us part 1, starfield etc.

By the time N48 and N44 launch that list will grow hence why I think N44 will be a 1080p card primarily and N48 will be a 1440p card primarily. Not saying you can't use them at higher resolutions because plenty of games will be fine but enough new AAA games won't be that I don't think they can advertise them as 1440p/4k cards with a straight face. OTOH AMD lied through their teeth in the RDNA 3 reveal so maybe they just do it anyway.
 
  • Like
Reactions: Tlh97

Timorous

Golden Member
Oct 27, 2008
1,748
3,240
136
The thing is that he said that the process is N4P, and looking at the perf/watt delta in respect of N5 and N6 this is perfectly in line with the stated frequencies in respect of a 7800XT and a 7600XT, that s exactly what to expect for 4 more CUs in the former case and same CU count for the latter while keeping the same TDPs at worse.

That assumes the same v/f curve which if so means AMD will have two duds on the trot. Not impossible but it would be a disaster for the client GPU market.
 

TESKATLIPOKA

Platinum Member
May 1, 2020
2,522
3,037
136
The thing is that he said that the process is N4P, and looking at the perf/watt delta in respect of N5 adn N6 this is perfectlly in line with the stated frequencies in respect of a 7800xt and a 7600XT, that s exactly what to expect for 4 more CUs in the former case and same CU count for the latter.
N32: 2430MHz 263W -> N48: 2770MHz (+340MHz)
Believable for comparable or lower TDP.

N33: 2655-2755MHz 165-190W -> N44: 2515-3515MHz
Either 140-240MHz lower clock than N33 using N6 process or 760-860MHz higher clock, which is 28-32% higher than N33.
Both are extremes regardless of how I look at It.
Ok, 3515MHz could be "believable" that AMD "fixed It" + better process, but memory BW should have been improved by a lot, but wasn't at all.
Then N48 also shouldn't have only 2770MHz, that's 745MHz difference between N44 vs N48! Then I would rather believe It's actually only 2515MHz but with much lower TDP.

If you want to believe that It's clockspeed + Typo, feel free to do so, but stop saying that I am wrong when you have no proof, It's just your speculation without even knowing the actual TDP.
 
Last edited:
  • Like
Reactions: Tlh97

Abwx

Lifer
Apr 2, 2011
11,557
4,349
136
That assumes the same v/f curve which if so means AMD will have two duds on the trot. Not impossible but it would be a disaster for the client GPU market.
Of course, that s very conservative, i assumed that nothing was fixed in respect of the v/f curve, so we can take this as a worst case that is unlikely to happen if they made some progress in this register.
 

Abwx

Lifer
Apr 2, 2011
11,557
4,349
136
Then N48 also shouldn't have only 2770MHz, that's 745MHz difference between N44 vs N48! Then I would rather believe It's actually only 2515MHz but with much lower TDP.

If you want to believe that It's clockspeed + Typo, feel free to do so, but stop saying that I am wrong when you have no proof, It's just your speculation without even knowing the actual TDP.
That s because the 32 CUs GPU goes from N6 to N4P while the 64 CUs start from N5, not counting that there s 4 more CUs, the smaller GPU has forcibly much more margin to increase frequency.

Edit : 2515MHz would mean that it would barely perform better than the 7600, and likely lower than the 7600XT, that just doesnt make sense.

7600XT clock up to 2760 and from N6 to N4P there s about 22% higher frequency at same power, that get us close to 3.4GHz, and that s assuming that the v/f curve is unchanged.
 
Last edited: