The last couple of weeks after the recent GeForce GTX 550 Ti launch have been more eventful than I had initially been expecting. As you may recall the GTX 550 Ti launched at $150, a price tag too high for its sub-6850 performance. I’m not sure in what order things happened – whether it was a price change or a competitive card that came first – but GTX 550 Ti prices have finally come down for some of the cards. The average price of the cheaper cards is now around $130, a more fitting price given the card’s performance.

The timing for this leads into today’s launch. AMD is launching a new card, the Radeon HD 6790, at that same $150 price point. Based on the same Barts GPU that powers the Radeon HD 6800 series, this is AMD’s customary 3rd tier product that we’ve come to expect after the 4830 and 5830. As we’ll see NVIDIA had good reason to drop the price on the GTX 550 if they didn’t already, but at the same time AMD must still deal with the rest of the competition: NVIDIA’s GTX 460 lineup, and of course AMD itself. So just how well does the 6790 stack up in the crowded $150 price segment? Let’s find out.

  AMD Radeon HD 6870 AMD Radeon HD 6850 AMD Radeon HD 5830 AMD Radeon HD 6790 AMD Radeon HD 5770
Stream Processors 1120 960 1120 800 800
Texture Units 56 48 56 40 40
ROPs 32 32 16 16 16
Core Clock 900MHz 775MHz 800MHz 840MHz 850MHz
Memory Clock 1.05GHz (4.2GHz data rate) GDDR5 1GHz (4GHz data rate) GDDR5 1GHz (4GHz data rate) GDDR5 1050MHz (4.2GHz data rate) GDDR5 1.2GHz (4.8GHz data rate) GDDR5
Memory Bus Width 256-bit 256-bit 256-bit 256-bit 128-bit
VRAM 1GB 1GB 1GB 1GB 1GB
FP64 N/A N/A 1/5 N/A N/A
Transistor Count 1.7B 1.7B 2.15B 1.7B 956M
Manufacturing Process TSMC 40nm TSMC 40nm TSMC 40nm TSMC 40nm TSMC 40nm
Price Point ~$200 ~$160 N/A $149 ~$110

3rd tier products didn’t get a great reputation last year. AMD and NVIDIA both launched such products based on their high-end GPUs – Cypress and GF100 respectively – and the resulting Radeon HD 5830 and GeForce GTX 465 were eventually eclipsed by the GeForce GTX 460 that was cooler, quieter, and better performing at the same if not lower price. The problem with 3rd tier products is that they’re difficult to balance; 1st tier products are fully enabled parts that are the performance kings, and 2nd tier products are the budget minded parts that trade some performance for lower power consumption and all that follows.

While 2nd tier products are largely composed of salvaged GPUs that couldn’t make it as a 1st tier product, the lower power requirements and prices make the resulting video card a solid product. But where do 3rd tier products come from? It’s everything that couldn’t pass muster as a 2nd tier product – more damaged units functional units that won’t operate at lower voltages like a 2nd tier product. The GTX 465 and Radeon HD 5830 embodied this with power consumption of a 1st tier card and the performance of a last generation card, which made them difficult to recommend. This does not mean that a 3rd tier card can’t be good – the Radeon HD 4830 and GTX 260 C216 were fairly well received – but it’s a difficult hurdle to overcome.

Launching today is the Radeon HD 6790, the 3rd tier Barts part and like the rest of the Barts-based lineup, the direct descendent of its 5800 series counterpart, in this case the Radeon HD 5830. As is to be expected, the 6790 is further cut-down from the 6850, losing 2 SIMD units and half of its ROPs; mitigating this some are higher clockspeeds for both the core and the memory. With 800 SPs and 16 ROPs operating at 840MHz, on paper the 6790 looks a lot like a Radeon HD 5770 with a 256bit bus, albeit one that’s clocked slower given the 6790’s 1050MHz (4.2GHz data rate) memory clock.

From the 5830 we learned that losing the ROPs hurts far more than the SPs, and we’re expecting much of the same here; total pixel pushing power is halved, and MSAA performance also takes a dive in this situation. Overall the 6790 has 90% of the shading/texturing, 54% of the ROP capacity, half the L2 cache, and 105% of the memory bandwidth of the 6850. Or to compare it to the 5770, it has 98% of the shading/texturing capacity, 98% of the ROP capacity, and 175% of the memory bandwidth, not accounting for the architectural differences between Barts and Juniper.

Further extending the 5830 comparison, as with the 5830 AMD is leaving the design of the card in the hands of their partners. The card being sampled to the press is based on the 6870’s cooler and PCB, as the 6790’s 150W TDP is almost identical to the 151W TDP of the 6870, however like the 5830 no one will be shipping a card using this design. Instead all of AMD’s partners will be using their own in-house designs, so we’ll be seeing a variety of coolers and PCBs in use. Accordingly while we can still take a look at the performance of the card, our power, temperature, and noise data will not match any retail card – power consumption should be very close however.

At 150W AMD is skirting the requirement for 2 PCIe power sockets. Being based on a 6870 our sample uses 2 sockets and any other design using a 6870 PCB verbatim should be similar, but some cards will ship with only a single socket. This doesn’t impact the power requirements of the card – it’s roughly 150W either way – but it makes the card more compatible with lower-wattage PSUs that only come with 1 PCIe power plug.

As we mentioned previously, AMD is launching the 6790 at $150. With the GTX 550’s price drop its direct competitor is no longer the GTX 550, but rather the closest competitor is now cheap GTX 460 768MB cards, which on average are about the same $150. AMD’s internal competition is the 6850, which averages closer to $160. Technically the Radeon HD 5770 is also competition, but with it going for around $110 after rebate, it’s far more value priced than the 6790 is.

Meanwhile the 6790 name also marks the first time we’ve seen the 6700 series in the retail market. In the OEM market AMD has rebadged the 5700 series as the 6700 series, however that change won’t ever be coming to the retail market, making this the only 6700 series card we’ll see. It’s a bit odd to see one series shared by two GPUs so significantly different, but AMD bases this on the fact that the 5770/6770 and the 6790 are so close in terms of specs; they want to frame the 6790 in terms of the 5770/6770, rather than in terms of the 6800 series. If nothing else it’s a nice correction for the poor naming of the 6800 series; a 6830 would have been the 5830 but slower.

April 2011 Video Card MSRPs
NVIDIA Price AMD
  $700 Radeon HD 6990
$480  
$320 Radeon HD 6970
$240 Radeon HD 6950 1GB
  $200 Radeon HD 6870
$160 Radeon HD 6850
$150 Radeon HD 6790
$130  
 
$110 Radeon HD 5770

 

The Test
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  • Amoro - Tuesday, April 05, 2011 - link

    I'm pretty sure that only Cayman is VLIW4. Reply
  • Ryan Smith - Tuesday, April 05, 2011 - link

    Correct. NI is a very broad family; it doesn't definite a single architecture. Cayman is VLIW4, Barts, Turks, and Caicos are VLIW5 and are basically optimized versions of Evergreen (5000 series) hardware.

    http://www.anandtech.com/show/3987/amds-radeon-687...
    Reply
  • Amoro - Tuesday, April 05, 2011 - link

    If you look at some of the raw performance specifications for the two cards it seems to indicate that texture fillrate and raw processing power don't have as much of an impact on Anandtech's testing suite.

    Radeon HD 5830

    Fillrates
    12.8GP/s
    44.8GT/s

    Memory Bandwidth
    128GB/s

    GFLOPS
    1792

    Radeon HD 6790

    Fillrates
    13.4GP/s
    33.6GT/s

    Memory Bandwidth
    134.4GB/s

    GFLOPS
    1344

    The 6790 wins in pixel fillrate and memory bandwidth but loses horribly in raw processing power and texture fillrate yet it still manages to keep within -10% and even manages to beat the 5830 in some cases.
    Reply
  • BoFox - Wednesday, April 06, 2011 - link

    Thanks for some more of those numbers!
    We can see that the 5830 has far higher numbers in these areas:
    44.8 GT/s
    1790 GFLOPs

    And the 6790 has only
    33.6 GT/s
    1344 GFLOPs

    While the 6790 has greater pixel fillrate and memory bandwidth than the 5830.

    If it were not for VLIW4, why is the 5830 only 2-3% faster than 6790 in this review here, if you look at all of the benchmarks? Why?

    Another way we could find out is to see how much it affects DP performance in applications like Milkyway@home. Cards with VLIW4 should have 1/4 the FP64 output ratio to FP32 output, so I wouldn't be surprised if we see 6790's being 20% faster than the similarly spec'ed 4890.
    Reply
  • BoFox - Thursday, April 07, 2011 - link

    Ahh, your article reminded me that FP64 was disabled for Barts GPUs.. I must've forgot about it and wanted to test it to prove that it's VLIW4.

    But the numbers in the replies below strongly point to the 6790 being boosted by VLIW4 in order to basically match up to a 5830 with 40% more shaders and TMU's.

    Any explanation for this, sir Ryan?
    Reply
  • BoFox - Friday, April 08, 2011 - link

    RE: "From a graphics point of view it's not possible to separate the performance of the ROPs from memory bandwidth. Color fill, etc are equally impacted by both. To analyze bandwidth you'd have to work from a compute point of view. However with that said I don't have any reason to believe AMD doesn't have a 256-bit; achieving identical performance with half the L2 cache will be harder though."

    1) If it's not possible to separate the performance from a "graphics" rather than "compute" point of view, then should not the performance be linked for all "graphics" point of views (as it is a "graphics" card to begin with)? Even the "compute" applications (FP16 and FP32 analysis at http://www.behardware.com/articles/783- ... -5830.html ) show the card to behave like as if it's 128-bit.
    2) Why does Ryan not have any reason to believe.. because AMD said so? If a manufacturer of a LCD panel advertises 1ms G2G response time, but it looks like 16ms, does he still have no reason to believe it's 16ms just because the manufacturer said so?
    3) If the L2 cache is cut down in proportion with the castrated shaders/TMUs/ROPs, then it should not affect performance, let alone "harder though".
    Reply
  • Soldier1969 - Tuesday, April 05, 2011 - link

    2 x 6970s FTW at 2560 x 1600 res. Reply
  • JimmiG - Tuesday, April 05, 2011 - link

    Is it just me or is all this talk about price difference of $10 or less getting a little ridiculous? I mean, if you're prepared to spend $150 (or $160...) on something that is completely non-essential, what difference is $10 going to make? If you're so poor that $10 is a big deal, you're probably not spending your money on gaming products anyway since you need everything for stuff like food and rent.

    It seems the video card companies are the guilty ones, constantly trying to outmaneuver each other with new pricing schemes. I miss the old days when there was one $100 card, one $200 card, one $300 card etc. Now there can easily be a dozen different models in the range of $100 - $300.
    Reply
  • liveonc - Tuesday, April 05, 2011 - link

    This looks like a prime candidate for a mini-ITX for those who'd want a desktop replacement, but don't want to pay so damn much for something that has 30minutes of battery life, doesn't have a chance to outperform a desktop, & costs too much. Reply
  • lorribot - Tuesday, April 05, 2011 - link

    Might be just me but since the 4000 series i dont actually understand AMDs numbering scheme anymore.
    There seem to be a great variety of of 6000 cards all with very similar performance and different prices.

    There is the 6990 at the top then a couple more 69xx cards then some 68xx and some 67xx, all well and good but it seems the 5870 is faster card then the 6870, which is odd and not what i would have expected, indeed it has similar performance to the 5850.

    The 5xxx series came in 53, 54, 55, 56, 57, 58 and 59 flavours with one, two or three sub versions in each band giving something like 15 or 16 different cards.

    It seems to me that with so many variations and a numbering scheme that seems to change from version to version AMD seem to actually want to confuse the buying public.

    They really need to get a handle on this, less is more in some cases.

    Nvidia's numbering scheme on the whole seems to be much more sensible in recent times, apart from the odd hiccup with 460 and 465.
    Reply

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