Thursday, December 8th 2011

AMD Radeon HD 7900 ''Tahiti'' Pictured, 384-bit Memory Bus Confirmed?

A Beyond3D forum member posted a mysterious picture of two graphics cards that could very well be engineering samples of AMD's true next-generation Radeon HD 7900 "Tahiti" graphics cards. The final products most probably won't look like these, with a bare red PCB, but it does look like the reference cooler design is ready. A more important feature in that picture is the spotting of traces for at least 11 memory chips, the 12th one (not highlighted) is apparently near the PCIe slot interface. The presence of 12 memory chips gives rumors of Tahiti featuring a 384-bit wide memory interface a shot in the arm. This will be the first AMD GPU in over 5 years to feature a memory bus wider than 256-bit. The R600 Radeon HD 2900 GPU featured a 512-bit GDDR4-capable memory interface.


Sources: Beyond3D Forums, VR-Zone
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117 Comments on AMD Radeon HD 7900 ''Tahiti'' Pictured, 384-bit Memory Bus Confirmed?

#1
radrok
Oh god can't wait, give me 2 no no wait 3 :roll:
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#2
robal
At last ! Some picture p0rn !
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#5
Aetherius
Cool! Im ready for these to release!! :D
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#6
btarunr
Editor & Senior Moderator
Let's play spot the 12th memory chip.

This?


BTW, that is a huge GPU package.
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#7
Zubasa
by: btarunr

BTW, that is a huge GPU package.
So is the GTX 580, and we know what a beast that is ;)
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#8
LAN_deRf_HA
Is there anything about the solder points on the back of those chips that indicates whether or not it's GDDR5/XDR?
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#9
radrok
Also found this magnification
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#10
Super XP
From what I've found out they are going with GDDR5. Also it seems AMD has been pushing for DDR memory for some time now. Though XDR would have been interesting indead. Now for the questions? Do I wait for another HD 6970 and do CrossfireX or do I sell my HD 6970, add a few more $$ and go for the upcoming HD 7970 :twitch: It all depends on Price/Performance :D
Posted on Reply
#11
radrok
by: Super XP
From what I've found out they are going with GDDR5. Also it seems AMD has been pushing for DDR memory for some time now. Though XDR would have been interesting indead. Now for the questions? Do I wait for another HD 6970 and do CrossfireX or do I sell my HD 6970, add a few more $$ and go for the upcoming HD 7970 :twitch: It all depends on Price/Performance :D
Just by experience, go for the newer series... AMD/ATI drivers have always been the best when using the latest gen cards
Posted on Reply
#12
btarunr
Editor & Senior Moderator
by: LAN_deRf_HA
Is there anything about the solder points on the back of those chips that indicates whether or not it's GDDR5/XDR?
Looking at the picture radrok posted, those traces look GDDR5. That said, it is rumored that Tahiti will feature support for both GDDR5 and XDR2, but they'll need two different PCB designs for GDDR5 boards and XDR2 ones. They're nowhere near pin-compatible. So this has to be that GDDR5 board.

Although there's just a small possibility that Tahiti will support XDR2, looking at these pictures is no way of dismissing that possibility. We'll have to wait for the products to actually launch, or any pre-release info to kill that "Tahiti-XDR2" rumor.
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#13
robal
by: LAN_deRf_HA
Is there anything about the solder points on the back of those chips that indicates whether or not it's GDDR5/XDR?
I doubt it.

Especially that XDR2 controller is compatible with GDDR5.
That means, even if it is integrated in Tahiti die, memory interfaces will look identical. Even same memory packages, probably.

Cheers,
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#14
radrok
If I were from AMD I would honestly fear to have something to do with Rambus even though XDR2 would have been surely intriguing
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#16
cadaveca
My name is Dave
Shit...maybe I'm totally off on what I'm expecting. How very interesting.

Sucks to see a red PCB, and dual 8-pin connectors though. 375W monster?

by: btarunr
Let's play spot the 12th memory chip.

This?
http://img.techpowerup.org/111208/bta4098dc.jpg

BTW, that is a huge GPU package.
What about the IOMMU that has been confirmed already? That could be used as teh "12th chip".


Shit. I was really expecting 128-bit IOMMU and 256-bit memory bus. Does GCN really need that much bandwidth? I'm so confused!!!
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#17
Super XP
by: radrok
If I were from AMD I would honestly fear to have something to do with Rambus even though XDR2 would have been surely intriguing
AMD can really benefit by using XDR2 memory. They just need to get some sort of aggreement in place so they cannot screw each other over. I mean RAMBUS can surely use the money and exposure by working with AMD.
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#18
Zubasa
by: radrok
If I were from AMD I would honestly fear to have something to do with Rambus even though XDR2 would have been surely intriguing
Guess what? Rambus has a hand in just about anything memory related.
Good luck avoiding them.
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#19
Super XP
by: cadaveca
Sucks to see a red PCB,
:eek: Let's keep ATI alive :toast:
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#20
btarunr
Editor & Senior Moderator
by: cadaveca
Sucks to see a red PCB
AMD high end card engineering samples (the ones made in Canada) have no backplate, and have red PCB. The mass production cards over the past two generations had black PCB and backplate.

by: cadaveca
What about the IOMMU that has been confirmed already? That could be used as teh "12th chip".


Shit. I was really expecting 128-bit IOMMU and 256-bit memory bus. Does GCN really need that much bandwidth? I'm so confused!!!
IOMMU can be integrated into the GPU die. It doesn't have to be a separate chip.
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#21
cadaveca
My name is Dave
I understand that iommu doesn't need a chip. that was my point.:laugh:

I've been talking about iommu for much longer than nearly anyone else. This has to be the most exciting thing about GCN for me. Most don't even have a clue what it'd be used for.
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#22
pantherx12
by: cadaveca
Shit...maybe I'm totally off on what I'm expecting. How very interesting.

Sucks to see a red PCB, and dual 8-pin connectors though. 375W monster?



What about the IOMMU that has been confirmed already? That could be used as teh "12th chip".


Shit. I was really expecting 128-bit IOMMU and 256-bit memory bus. Does GCN really need that much bandwidth? I'm so confused!!!
It's 2 x 6 pin dude, although having said that the card underneath is 8 and 6.
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#23
X800
I found this picture.
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#24
btarunr
Editor & Senior Moderator
by: X800
I found this picture.
Nice, so the missing chip (marked 1 in that picture) is right where we thought it would be.
Posted on Reply
#25
cadaveca
My name is Dave
by: pantherx12
It's 2 x 6 pin dude, although having said that the card underneath is 8 and 6.
Um, that's not what I see(I see 8+6 in both cards, and pinout for 8x8):

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