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AMD's Radeon HD 4870 X2: R700 First-Look

A Secret Weapon Exposed: Specs

As is the case with Intel’s Core 2 Duo and its shared L2 cache, it’d be ideal if both of the 4870 X2’s GPUs could both access the 2 GB frame buffer. Despite the persistent rumors surrounding this new card, those capabilities simply aren’t possible at this time. However, the two GPUs do have a new side-port interface between them able to contribute additional bandwidth should the PCI Express 2.0 bus become saturated.

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AMD confirms for us that this communication pathway isn’t currently being utilized and that it will really only need to do so in the next few months by way of software. According to representatives at AMD, today’s applications do well enough with the throughput available through PCI Express, meaning the side-port connection wouldn’t really add much to the card’s performance picture anyway. For now, the Radeon HD 4870 X2 enjoys enough of a speed-up thanks to the addition of a PCI Express 2.0 bridge linking its two GPUs. In fact, we wouldn’t be surprised if the side-port feature never really takes off in this generation of hardware.

GPUHD 4870HD 4870 X2GTX 280
GPU Frequency750 MHz750 MHz602 MHz
ALU Frequency750 MHz750 MHz1296 MHz
Memory Frequency900 MHz900 MHz1107 MHz
Width of the Bus Memory256 bits2 x 256 bits512 bits
Memory TypeGDDR5GDDR5GDDR3
Memory Quantity512 MB2 x 1 GB1 GB
Number of ALUs8001600240
Number of texturing units408080
Number of ROP163232
Shading Power1.2 TFlops2.4 TFlops933 GFlops
Memory Bandwidth115.2 GB/s115.2 GB/s (x2)141.7 GB/s
Number of transistors956 million2 x 956 million1.4 billion
Process Technology55 nm55 nm65 nm
Surface die260 mm²2 x 260 mm²576 mm²
Generation200820082008
DirectX Supported10.110.110

AMD has quadrupled the amount of memory on the Radeon HD 4870 X2 versus its existing Radeon HD 4870, although we are expecting to see a 1 GB version of the company’s single-GPU desktop board soon. For all intents and purposes, the X2 behaves like a card equipped with 1 GB of available memory, just like the GeForce GTX 280. Another point point to mention: memory frequency. Whereas AMD had to reduce the speed of the memory on its Radeon HD 3870 X2, the 4870 X2 runs at the same frequency as single-chip 4870 cards. The GPUs haven’t slowed down at all, either. That’s good news, especially given the big board’s power consumption, which we suspected might limit its potential headroom. AMD is clearly gunning for the performance title on this one.

  • randomizer
    How's the microstutter?
    Reply
  • tipmen
    Good job ATI/AMD! really good card you have here lets hope its cheaper then the GTX 280. I'm glad i waited it out now i can replace my old setup. Now i will get new X48 board and 2 of these puppys and im sure I need a better power supply I don't think a 750 watt will do it.
    Reply
  • kite212
    looks like i need a new mobo and a bigger case to fit this beast
    Reply
  • Whoa, what happened to the heat and power consumption level charts? Where they that far off the scale you dare not show them? The card performs nicely but this is ATI/AMD we are talking about, they love heat and power. So what are they?
    Reply
  • Cmhone
    It says at the end of the article their power meter went kaput, and also not to expect much in the power consumption department anyways.
    Reply
  • neiroatopelcc
    Someone explain to me what this means in english?
    "Back when we tested the Radeon HD 3870 X2, we found that the biggest impact on performance was attributable to the board’s memory capacity, since memory on a bi-GPU card has to be divided in two. And in order to assure adequate performance, you often have to multiply the quantity of memory by four, which is what AMD does with the 4870 X2." from page 1
    Reply
  • romulus47plus1
    I can smell incoming price drops...
    Reply
  • It's nice to see AMD/ATI challange nVidia again, it's been too long nVidias market. My take is that this situation can only benefit the consumers; push for faster GPU's to more affordable prices. It will be interesting to see nVidias run to retake the performance as well as the midrange price/performance crown.
    Reply
  • randomizer
    neiroatopelccSomeone explain to me what this means in english? "Back when we tested the Radeon HD 3870 X2, we found that the biggest impact on performance was attributable to the board’s memory capacity, since memory on a bi-GPU card has to be divided in two. And in order to assure adequate performance, you often have to multiply the quantity of memory by four, which is what AMD does with the 4870 X2." from page 1The HD3870X2 had only 2x512MB memory, and each GPU could only access 512MB, which held its performance back. Although I think it should say "doubled", not "quadrupled", since the HD4870X2 has 2x1GB.
    Reply
  • Thurin
    .............................
    Point 1:
    It's great that Ati is putting up a fight and it's obvious that with all fan-boys and trash talking/flaming aside the only reason why this rapid progression on a pure processing and on the overall technological level is made possible through competition between the titans of the graphics processing world.
    .............................

    BUT!

    According to other valued/trustworthy sources the 4870 X2 manages only a 1.09 over 1.00 increase in performance.

    see link:
    http://tweakers.net/reviews/957/4/his-radeon-hd-4870-x2-versus-asus-geforce-gtx-280-pagina-4.html (Copy paste the link if needed)
    .............................

    As for the significant increase stated in this article, it's great, but only applicable to those games with integrated support for crossfire technology. (Further and extensive testing would be desirable, and posting actual facts to support claims would also be duly noted. // I know some testing has been done, but a full review on exactly what value is added with the new card, still remains to be seen.)

    .............................
    Point 2:
    As for NVidia's reply to the 4870 X2 dual-gpu card is the introduction of the 65 nm -> 55nm gpu chipsize reduction.

    Link:
    http://tweakers.net/nieuws/55050/introductie-55nm-versie-geforce-gtx-280-eind-augustus.html

    According to the news this is to take place at the end of August. meaning that the reply is ready and launched by the end of THIS month.
    .............................

    I would like to at this point state I'm not a fan boy for either side, and I myself have switched from Nvidia to Ati back to Nvidia and will keep doing this as either side dominates the market with high quality merchandise and depending on which one is the market leader at the points where I update my machines.
    .............................

    My apologies to those of you who cannot read or understand Dutch.

    Here is a substitute link for the interested English parties:
    http://www.stokedgamer.com/2008/07/nvidia-geforce-gtx-290-launching-at.html

    The reason I responded with such diligence and ferocity is not because I hate Tomshardware, think that Ati is doing a bad job or that NVidia rocks beyond compare... The reason for my reply is that I wish for the consumer to be fully informed and not end up buying a more expensive product for less bang/buck than originally expected.

    Stay informed folks ! (For those of you who have a no limit budget the 4870 X2 might be the way to go, other than that, if you are looking for a more financially affordable card, wait for the 55nm NVidia GTX280 revision (name is yet to be determined, release expected at the end of the month))

    That concludes my rant for the day and I hope you guys are now fully informed or that I have at least have sparked your interest on the field of gathering information before drawing a conclusion based on a single review ;)

    Look around! and stay informed ! Ati and Nvidia both rock and the best of luck to both companies... may the struggle be eternal and the progress fiery and extreme!

    .............................

    -= Michael Out =-
    Reply