ATI Radeon HD 4770: 40nm Goes Mainstream

Radeon HD 4770: Speeds And Feeds

Superficially, the Radeon HD 4770’s specs look fairly similar to ATI’s Radeon HD 4830. But they’re completely unique GPUs. For example, the 4830 centers on the familiar 956 million transistor RV770 with two of its 10 SIMD units disabled, yielding 640 total stream processors and the ability to filter 32 textured pixels per clock (down from 800 and 40, respectively).

ATI’s Radeon HD 4830 retained all four of the RV770’s render back-ends (each of which could process four pixels and 16 Z/stencil operations per clock—that’s why you see these cards spec’ed out with 16 ROPS). The memory controllers carried over as well, enabling the same 256-bit memory bus employed on Radeon HD 4850 and 4870 boards. The main difference, of course, was that the 4850 and 4830 were only armed with GDDR3, while the 4870 sported GDDR5.

In comparison, the Radeon HD 4770’s architecture employs an 826 million transistor GPU armed with the same number of SIMD units available (eight). It also boasts 640 stream processors (128x5) and 32 texture units. So, from a front-end view, RV740 looks a lot like the RV770 after it was chopped up to become Radeon HD 4830.

The full complement of ROPs carries over too, processing 16 pixels and 16 Z/stencil ops per clock. Where you’ll notice the most significant difference is the memory configuration—two of the four 64-bit controllers are cut, leaving a 128-bit pathway. Because those memory controllers are connected to the render back-ends via a hub, they don’t need to be mapped on a 1:1 basis.

Now, you’d assume the halved memory bus (down from 256-bits) would hammer performance. But ATI is outfitting the Radeon HD 4770 with 512 MB of GDDR5 memory, able to move twice as much data per clock versus GDDR3. So, the 4770’s throughput actually turns out to still be respectable for a mainstream part.

The shift to 40 nm has seemingly allowed ATI to push clocks on its Radeon HD 4770 significantly higher than what it was willing to offer on the 4830. Stock, the GPU runs at 750 MHz (versus the 4830’s 575 MHz).

Though the 800 MHz memory clock would appear slower than the 4830’s 900 MHz operating frequency, it’s important to remember that GDDR5 provides doubled I/O throughput. Of course, the card’s 128-bit counteracts those benefits. Whereas Radeon HD 4830 served up roughly 57.6 GB/s, the 4770 pushes 51.2 GB/s.  

Another benefit of the 40 nm transition is reduced board power. ATI claims the 4770 is rated for a maximum 80W, putting it just over what a PCI Express slot is able to supply on its own. That’s well under the 110W cited for the Radeon HD 4850, though—a board that we’ll see is within the 4770’s performance crosshairs.


Radeon HD 4850
Radeon HD 4830
Radeon HD 4770
Radeon HD 4670
GeForce GTS 250
Manufacturing Process55 nm TSMC55 nm TSMC40 nm TSMC55 nm TSMC55 nm TSMC
SPs800
640640320
128
Core Clock625 MHz575 MHz
750 MHz750 MHz
738 MHz
Shader Clock625 MHz575 MHz750 MHz750 MHz
1,836 MHz
Memory Clock1,000 MHz GDDR3
900 MHz GDDR3
800 MHz GDDR51,100 MHz GDDR4
1,100 MHz GDDR3
Frame Buffer512 MB
512 MB
512 MB
512 MB
1 GB
Memory Bus Width256-bit
256-bit
128-bit
128-bit
256-bit
ROPs16
16
16
8
16
Price~$129
~$90$109
$80
~$129
Create a new thread in the US Reviews comments forum about this subject
This thread is closed for comments
103 comments
    Your comment
    Top Comments
  • bardia
    I'm pretty blown away at the kind of performance that can be had for ~$100 these days thanks to ATI. It wasn't long ago when Nvidia forced us to choice between the incredibly crappy 8600GT for $150 and the ~$250-300 8800GTS 320.

    ATI is leading us into graphics nirvana.
    31
  • Summer Leigh Castle
    bardiaI'm pretty blown away at the kind of performance that can be had for ~$100 these days thanks to ATI. It wasn't long ago when Nvidia forced us to choice between the incredibly crappy 8600GT for $150 and the ~$250-300 8800GTS 320.ATI is leading us into graphics nirvana.

    I spent almost $300 on my 8800GTS 320 OC when they came out and I thought I got a great deal. Things have changed! Competition = good for the consumers!
    14
  • RazberyBandit
    Good write-up, Chris. Two points of criticism, one of high praise.

    First, I would have preferred to see a whole line of 512MB cards - Tossing a 1GB GTS into the mix makes the higher rez comparisons rather unfair. Given that the typical cost of a 1GB version of the GTS250 is is typically $150-$160 (~$140 w/ MiR), not the $120-$130 price you purport, (those around $120 or so are the 512MB cards) there is more to that story than just the amount of VRAM.

    Second, the part about DX10 vs DX10.1 where you said the following:
    Quote:
    At 1920x1200, the Radeon HD 4850 achieves 12.7 frames per second with “Use DX 10.1” checked (compared to 11.3 frames without it). Looking for a more playable frame rate, we dropped to 1280x1024 and recorded 21.35 frames—down from 21.5. The moral of the story? Don’t expect DX 10.1 to make this title any more playable than it was without the feature enabled.

    Why didn't you perform that specific switch on the 4770? I mean, that's the card the article is focused upon, right? Just seems more prudent to apply that to the focus card.

    Lastly, I particularly liked the comparison where you went from the "king" i7 to the budget-oriented X2 Kuma. It clearly showed the benefit of a much faster CPU and it's associated architecture in games that are clearly CPU-dependent.
    12
  • Other Comments
  • Dekasav
    "Well-played ATI, well played."

    Couldn't say it better, myself.

    Looks to be a pretty good card, but nothing spectacular. 40nm is nice, a little cheaper HD 4850 (fewer FPS, too), but all in all, nicely done.

    I wonder who'll sell more, now, the 4850 or the 4770?
    5
  • Anonymous
    "The card’s strange behavior continues on the CPU-only test, where it takes a nearly 2,000-point hit for no good reason" maybe because of the 128 bit memory bus
    -11
  • kelfen
    solid card for the average gammer ;)
    4
  • bardia
    I'm pretty blown away at the kind of performance that can be had for ~$100 these days thanks to ATI. It wasn't long ago when Nvidia forced us to choice between the incredibly crappy 8600GT for $150 and the ~$250-300 8800GTS 320.

    ATI is leading us into graphics nirvana.
    31
  • pharge
    Wondering will 4770 a good one for crossfire? Can we have a review on it....? With its low power useage when fully loaded, cheaper price (~$40 cheaper than 4850 when CF), not much slower than 4850 (512MB), and nice overclocking range... It will be nice to see will 4770 CF setup be useful (playable) in games (1920x1200) with some visual goodies truned on.
    10
  • Anonymous
    Wondering about 4770x2, should be wishful item
    2
  • Summer Leigh Castle
    bardiaI'm pretty blown away at the kind of performance that can be had for ~$100 these days thanks to ATI. It wasn't long ago when Nvidia forced us to choice between the incredibly crappy 8600GT for $150 and the ~$250-300 8800GTS 320.ATI is leading us into graphics nirvana.

    I spent almost $300 on my 8800GTS 320 OC when they came out and I thought I got a great deal. Things have changed! Competition = good for the consumers!
    14
  • eklipz330
    this card is amazing for 1680x1050, if they can manage to slap some aftermarket coolers on there, buying two for the price of a 1gb 4870, and overclocking them, im pretty sure we'd pass gtx 285 numbers.... simply amazing.

    great card for 16x10 resolution. good job ati, you've done more damage to nvidia[and they're sickly pricing schemes] in the past year than they've done to you in the pass 3-4
    5
  • eklipz330
    *edit*

    just checked newegg and they all have aftermarket coolers on them... wow *_*

    http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&DEPA=0&Order=BESTMATCH&Description=4770&x=0&y=0
    0
  • Ryun
    eklipz330*edit*just checked newegg and they all have aftermarket coolers on them... wow *_*http://www.newegg.com/Product/Prod [...] 70&x=0&y=0


    Nah, they're reference coolers from AMD. From what I heard, AMD gave the AIB partners a choice between the dual slot and the, for lack of a better term, uglier cooler. Apparently the "uglier" one is cheaper so that's what you're probably going see for now.
    1
  • aznguy0028
    RyunNah, they're reference coolers from AMD. From what I heard, AMD gave the AIB partners a choice between the dual slot and the, for lack of a better term, uglier cooler. Apparently the "uglier" one is cheaper so that's what you're probably going see for now.

    i actually like the "uglier" coolers. they look like a spaceship on the card xD. haha
    2
  • Anonymous
    You guys at Tom's are really pathetic. Not only using an early sample of 4770 but pitting it against 1 GB GTS which is in totally different price category. Why didn't you use GTX285 to make nvidia look even better? And that CUDA hyping at the end. Come on, normal person won't need GPU video acceleration. There is no limit in your nvidia bias.
    -20
  • JAYDEEJOHN
    Im just hoping they spend as much space, and lines on ATI's DX10.1 whenever nVidia releases something, or in an nVidia review coming
    2
  • anamaniac
    It will play Crysis!
    Now to see, will it crossfire with a 4670? That'd be orgasmic.
    I luv my 4670, but I also want the 4770... :'(

    I love seeing low power cards also. I'm too cheap to buy a good PSU.
    All the cards on newegg look exactly the same...
    -8
  • thepinkpanther
    dang i thought the 4770 would suck compared to any 256 bit interface card,boy! was i wrong!
    4
  • Ryun
    aznguy0028i actually like the "uglier" coolers. they look like a spaceship on the card xD. haha


    Maybe bulkier would've been a better term? =)

    Sorry it's late and I'm working on a web computing project so my vernacular is a little narrow.
    -4
  • crisisavatar
    excellent card but i think the extra 10 bucks made it loose some of it's charm.
    6
  • cangelini
    phargeWondering will 4770 a good one for crossfire? Can we have a review on it....? With its low power useage when fully loaded, cheaper price (~$40 cheaper than 4850 when CF), not much slower than 4850 (512MB), and nice overclocking range... It will be nice to see will 4770 CF setup be useful (playable) in games (1920x1200) with some visual goodies truned on.


    This is upcoming. I know they were asking for CrossFire in other countries as well, but we didn't receive two of these boards. There is a Radeon HD 4770 roundup in the works, however!
    6
  • NuclearShadow
    The price to performance ratio just keeps getting better and better. I'm simply amazed by this.
    1
  • RazberyBandit
    Good write-up, Chris. Two points of criticism, one of high praise.

    First, I would have preferred to see a whole line of 512MB cards - Tossing a 1GB GTS into the mix makes the higher rez comparisons rather unfair. Given that the typical cost of a 1GB version of the GTS250 is is typically $150-$160 (~$140 w/ MiR), not the $120-$130 price you purport, (those around $120 or so are the 512MB cards) there is more to that story than just the amount of VRAM.

    Second, the part about DX10 vs DX10.1 where you said the following:
    Quote:
    At 1920x1200, the Radeon HD 4850 achieves 12.7 frames per second with “Use DX 10.1” checked (compared to 11.3 frames without it). Looking for a more playable frame rate, we dropped to 1280x1024 and recorded 21.35 frames—down from 21.5. The moral of the story? Don’t expect DX 10.1 to make this title any more playable than it was without the feature enabled.

    Why didn't you perform that specific switch on the 4770? I mean, that's the card the article is focused upon, right? Just seems more prudent to apply that to the focus card.

    Lastly, I particularly liked the comparison where you went from the "king" i7 to the budget-oriented X2 Kuma. It clearly showed the benefit of a much faster CPU and it's associated architecture in games that are clearly CPU-dependent.
    12