• Guest, The rules for the P & N subforum have been updated to prohibit "ad hominem" or personal attacks against other posters. See the full details in the post "Politics and News Rules & Guidelines."

Question Speculation: RDNA2 + CDNA Architectures thread

Page 176 - Seeking answers? Join the AnandTech community: where nearly half-a-million members share solutions and discuss the latest tech.

Shivansps

Diamond Member
Sep 11, 2013
3,394
1,001
136
With SAM, we get 64GB/s fed to the CPU, instead of 25-ish for the DDR4-RAM. Thats quite a difference. Look ahead and PCIex gen 5 will deliver 128GB/s to the CPU. Might as well throw those sticks of RAM out the window, just buy a AMD 8900XT with 48 Gigs of GDDR7 feeding the CPU with the SAM-Ex-ALLCPU feature.. ;D
Well i was thinking exactly about this... what AMD managed to do is probably to add the GPU memory address range after the main system ram range... This should make possible, at least in theory, to use GPU memory as system ram.
 
  • Like
Reactions: kurosaki

DDH

Member
May 30, 2015
167
168
111
300W Total Board Power for RX 6900XT and 6800 XT and 250W TBP for 6800 is with USB-C 30W.

Have a nice day :).
I wondered about that. Total board power would theoretically mean the max power the board would chug under the most strenuous load, so while 100% GPU load and USBc output?

Have you seen confirmation of this somewhere?

Nvidias 20 series had USBC right? So were their tbp numbers inclusive of USBC power delivery too?
 

Elfear

Diamond Member
May 30, 2004
7,040
558
126
Well the 3080 does better vs old architecture at 4k vs 1440p, most just assumed this was because of being more CPU bound, which may be part. But seemed more due to it's design, sort of reminded me of was it Vega, which also was relatively slower at lower resolutions but did better as resolution increased.
Hardware Unboxed did an interesting analysis about the doubling of the FP32 throughput in Ampere being the reason they really come alive at 4k. Link to post with more info.
 

Glo.

Diamond Member
Apr 25, 2015
4,841
3,461
136
I'm giving serious consideration to an all-AMD build, which I've never done before. 5900X + 6800XT, anyone? Hmmm. Maybe.

I'll see if independent reviews push me over the edge.
I myself will build, for my first time in my life full AMD build with first time AMD GPU owner here :)

Ryzen 5 5600 + Navi 23 based GPU will fit the bill :).
 

Glo.

Diamond Member
Apr 25, 2015
4,841
3,461
136
I wondered about that. Total board power would theoretically mean the max power the board would chug under the most strenuous load, so while 100% GPU load and USBc output?

Have you seen confirmation of this somewhere?

Nvidias 20 series had USBC right? So were their tbp numbers inclusive of USBC power delivery too?
Yes. No. Maybe?

Just wait for reviews, till this will be proven right or wrong ;).
 

sze5003

Lifer
Aug 18, 2012
13,590
363
126
I'm giving serious consideration to an all-AMD build, which I've never done before. 5900X + 6800XT, anyone? Hmmm. Maybe.

I'll see if independent reviews push me over the edge.
Also thinking of this for the first time too. But I have a gsync only monitor so not really convinced 100% yet.
 

PhoBoChai

Member
Oct 10, 2017
119
389
106
Hardware Unboxed did an interesting analysis about the doubling of the FP32 throughput in Ampere being the reason they really come alive at 4k. Link to post with more info.
That's the correct analysis. Some graphics workload are resolution independent, as in they don't change much, relative to the pixel increase of higher resolution.

What scales with res, are compute and pixel shaders, screen space effects, RT, etc.

3080 and 3090 has far too much FP32 ALUs for its identical to 2080Ti performance in vertice, geometry, and raster. And only a tiny bit more texture performance. So its imbalanced. Requires high res to showcase the 2x FP32 gains.

Big Navi doesn't have an excess of compute like GCN, relative to front & back end performance. It's more balanced for graphics/gaming, and performs well across the different resolutions.
 
  • Like
Reactions: moinmoin and Elfear

Justinus

Platinum Member
Oct 10, 2005
2,748
861
136
You know, "Above 4G Decoding" sure sounds an awful lot like resizable/large BAR support.... A.K.A. Smart Access Memory...

I wonder if it will work on systems where the driver detects full mapping of VRAM, if it will be limited due to some proprietary synergy with Zen 3, or if it will be artificially locked out.
 

randomhero

Member
Apr 28, 2020
120
183
76
Has anyone thought of IC in CDNA?
Rumoured die size is huge, close to reticle limit. There is no graphics and video output related hardware, although it has fp64 and AI related hardware and extra 48 CU.Memory controller should be about same since it uses 4096 bit HBM.
 
  • Like
Reactions: lightmanek

PhoBoChai

Member
Oct 10, 2017
119
389
106
Has anyone thought of IC in CDNA?
Rumoured die size is huge, close to reticle limit. There is no graphics and video output related hardware, although it has fp64 and AI related hardware and extra 48 CU.Memory controller should be about same since it uses 4096 bit HBM.
It's going to have either tweaked CUs to accelerate tensor ops, or dedicated tensor cores. Lots and lots of SRAM cache for HPC and big data acceleration.
 

PhoBoChai

Member
Oct 10, 2017
119
389
106
  • Like
Reactions: lightmanek

uzzi38

Golden Member
Oct 16, 2019
1,889
3,805
116
It's highest setting for RT Shadows in the menu.

46FPS @ 4K

80FPS @ 1440p

Max settings.

6800.

WTF! That's faster RT than expected from all the rumors.

6800 has 60 SM, so 60 "Ray Accelerators", vs 68 in the 3080.
I bet you now that the whole Infinity Cache thing is helping out a huge deal.

At the same time though, I'm not expecting a huge improvement to RTRT as you move up the stack. This looks only 10% behind the 3080, if I were to guess the 6800XT and 6900XT will probably be closer to the 3080 with the 3090 on top.

(Not to take anything away from AMD - this sort of performance is well past what I expected from the hugely cut down 6800).
 

kurosaki

Senior member
Feb 7, 2019
257
247
86
I bet you now that the whole Infinity Cache thing is helping out a huge deal.

At the same time though, I'm not expecting a huge improvement to RTRT as you move up the stack. This looks only 10% behind the 3080, if I were to guess the 6800XT and 6900XT will probably be closer to the 3080 with the 3090 on top.

(Not to take anything away from AMD - this sort of performance is well past what I expected from the hugely cut down 6800).
I'm seeing it in front of me, how Lisa just wawes off the comments around the top notch RT performance after the flaming hot reviews with an, "of course our RT is better".
 
  • Haha
Reactions: lightmanek

soresu

Golden Member
Dec 19, 2014
1,701
885
136
I'm seeing it in front of me, how Lisa just wawes off the comments around the top notch RT performance after the flaming hot reviews with an, "of course our RT is better".
Even if RT isn't perfect this gen it's still enough to get the job done for a first shot, and you just know that RDNA3 will bring improvements as Zen3 did for gamers.

Cue nVidia trying to push out Far Cry fully Path Traced edition to make AMD look bad in the interim.
 
  • Like
Reactions: uzzi38 and kurosaki

ASK THE COMMUNITY