ATI Radeon HD 4000 Series discussion

[Kai Robinson]

One thing i'm slightly confused about....it looks to me like the shader speed is the same as the core clock, is this the case, or are the shaders in a separate clock domain now?

[003]

I think the 1 Ghz rumours came from people trying to reverse engineering the claimed flop counts based on only 480 shaders.

Thats the most plausible explanation I've heard so far.

[Cecil]

The 1050 core clock was mixed up with the shaders. It was in another language and someone saw 1050mhz and thought that was the core. Core is 850, shaders are 1050. 1000+ shouldnt be too hard though, seing as it has two power plugs at 75w each, plus the 75w from the mobo, so its getting plenty of power. Just need some good cooling, maybe a v-mod.

[003]

No you guys are way too cool, I'll stay here

No hard feelings. Oh, guys, first official shots of the 4870X2 have emerged!!! See here:

[disruptfam]

lol.

[perkam]

No hard feelings. Oh, guys, first official shots of the 4870X2 have emerged!!! See here:

That's cruel yet funny

Perkam

[Bo_Fox]

yeah thats cruel how it's so life-threatening to your poor computer!

[superbowtie]

No hard feelings. Oh, guys, first official shots of the 4870X2 have emerged!!! See here:

chasing dust bunnies no doubt!

[Luka_Aveiro]

No hard feelings. Oh, guys, first official shots of the 4870X2 have emerged!!! See here:

Terrible ca(t)ble management

[Isaac MM]

Can someone please tell me the specs of the 4850, the 4870 and the 4870x2(are they out yet?)? There is too much info on this thread and it will be hard to search all these pages. Thanks

[Extelleron]

Can someone please tell me the specs of the 4850, the 4870 and the 4870x2(are they out yet?)? There is too much info on this thread and it will be hard to search all these pages. Thanks

Both HD 4850 & HD 4870:

-RV770 Core (55nm)
-800 stream processors
-32 TMU / 16 ROP
-256 Bit Memory Bus

HD 4850:
-625MHz Core
-512MB GDDR3 @ 2000MHz

HD 4870:
-750MHz Core
-512MB GDDR5 @ 3600MHz

HD 4870 X2
-???MHz Core
-1024MB GDDR5 @ ????MHz

[ORBR]

Yeah, though unless DAAMIT have managed to overcome a basic limitation of these solutions you will still have 512mb of usable memory (frame buffer) on the crossfire setup, and also half the bus width of the 280.

No,
if you say that the data is doubled in the two banks of 512 MB each, then you can think about the two 256 bit bus as one 512 bit bus

[GoldenTiger]

No,
if you say that the data is doubled in the two banks of 512 MB each, then you can think about the two 256 bit bus as one 512 bit bus

No, you can't... it is simply copied individually per-chip across its own individual 256-bit bus to its own bank of 512MB, there is no intercommunication that combines the bandwidths.

[ORBR]

No, you can't... it is simply copied individually per-chip across its own individual 256-bit bus to its own bank of 512MB, there is no intercommunication that combines the bandwidths.

why don't
in AFR one bus is used fully with frame A, another with frame B

so why can't I consider this as powerful as one wide bus?

there's no need for intercommunication between the two chip

[GoldenTiger]

why don't
in AFR one bus is used fully with frame A, another with frame B

so why can't I consider this as powerful as one wide bus?

there's no need for intercommunication between the two chip

Yes, but the exact same data is copied on each 256-bit bus, therefore it is not seperate and able to be "added together" and considered a "one wide bus".

[ORBR]

Yes, but the exact same data is copied on each 256-bit bus, therefore it is not seperate and able to be "added together" and considered a "one wide bus".

this is false my friend
each chip write different data on its bus, and you're sure they read the same ONLY if they work on the same (doubled in each memory bank) framebuffer
with AFR they can read slight different assets

and with crossfire you have doubled not only bus and shaders, but buffers TOO, making the way the bus works more efficient

finally I can consider two 256 bit bus as powerful as one 512 bit bus

[GoldenTiger]

this is false my friend
each chip write different data on its bus, and you're sure they read the same ONLY if they work on the same (doubled in each memory bank) framebuffer
with AFR they can read slight different assets

and with crossfire you have doubled not only bus and shaders, but buffers TOO, making the way the bus works more efficient

I can consider two 256 bit bus as powerful as one 512 bit bus

I HIGHLY suggest you educate yourself before posting such claims that are technically impossible. What you describe is a shared architecture, not a CrossFire/SLI setup.

[ORBR]

I HIGHLY suggest you educate yourself before posting such claims that are technically impossible. What you describe is a shared architecture, not a CrossFire/SLI setup.

fell free to explain and to post evidence before tell at the people "to educate"
thanks

[oohms]

I think what he is saying is that the 2 cards each have their own 256 bit bus, but because each card is working on its own workload it effectively becomes 512 bits of memory bandwidth.
(Not that its the way i would explain it.)

[fcry64]

HD 4870 X2
-775MHz Core
-1024MB GDDR5 @ 3800MHz - 3900MHZ

HD 4850 X2
-600 - 625MHZ core
-1024MB GDDR3 @ 2000MHZ - 2100MHZ

[Taoof]

what are you talking about? r700??

[fcry64]

hey taof welcome to XS!

yeah its teh rv700

[DilTech]

this is false my friend
each chip write different data on its bus, and you're sure they read the same ONLY if they work on the same (doubled in each memory bank) framebuffer
with AFR they can read slight different assets

and with crossfire you have doubled not only bus and shaders, but buffers TOO, making the way the bus works more efficient

finally I can consider two 256 bit bus as powerful as one 512 bit bus

In a perfect world, maybe.

You see, both GPU's have to store the same information, EVEN IF IT'S AFR mode! Why? Because 99% chance says Frames 1,3,5,7,9, and 11 have 90% the same information(textures, shaders, etc) as 2,4,6,8,10, and 12.

You see, when you run multiple cards, both cards must have all the information in their individual memory banks, as both cards are likely to be showing the same textures as one another, as well as the same shaders. As such, you're effectively doubling the same exact info in both physical memory, as well as using the memory bandwidth of both cards to perform identical tasks. Seeing as how they can't share the same information from the same set of ram, they're effectively doing the same job twice.

As such, it's the same as a single 256bit memory bus, and a single set of 512mb of ram. That's why most stores make sure to specify 256bit x2 and 512mb x2. 2x256bit doesn't equal 512bit.

[Chickenfeed]

That's why most stores make sure to specify 256bit x2 and 512mb x2. 2x256bit doesn't equal 512bit.

Sadly in many cases with marketing, the 9800GX2 and 3870X2 are labeled as 1GB 512bit cards. Like you said, most online stores aren't so ignorant but the actual board makers themselves are guilty of this on their own boxes, which I find quite amusing. Obviously it sounds better than just 512x2 but its somewhat dishonest. The funny thing though is the people who buy these cards are usually the people who would know better and aren't impulse buyers ( and usually consumers who've done their research; people don't tend to impulse buy $500-600 video cards without knowing much about them ) Good old marketing departments for you.

I forgot there will still be 4850X2s as well. Those may turn out to be quite attractive options.

[madcho]

vrzone :

http://forums.vr-zone.com/showthread.php?t=289000

seems fake : 480SP