August is not typically a busy time of the year for the GPU industry. But this is quickly turning out to be anything but a normal August. Between professional and consumer graphics cards we have a busy week ahead.

Kicking things off on the consumer side today, AMD is announcing that they will be releasing a new Radeon HD 7950 with higher clockspeeds. The new 7950, to be called the Radeon HD 7950, is a revised version of the existing 7950 that is receiving the same performance enhancements that the 7970 received back in June, which were the basis of the Radeon HD 7970 GHz Edition.

AMD GPU Specification Comparison
  AMD Radeon HD 7970 GHz Edition AMD Radeon HD 7970 AMD Radeon HD 7950 (w/Boost) AMD Radeon HD 7950
Stream Processors 2048 2048 1792 1792
Texture Units 128 128 112 112
ROPs 32 32 32 32
Core Clock 1000MHz 925MHz 850MHz 800MHz
Boost Clock 1050MHz N/A 925MHz N/A
Memory Clock 6GHz GDDR5 5.5GHz GDDR5 5GHz GDDR5 5GHz GDDR5
Memory Bus Width 384-bit 384-bit 384-bit 384-bit
FP64 1/4 1/4 1/4 1/4
Transistor Count 4.31B 4.31B 4.31B 4.31B
PowerTune Limit 250W+ 250W 225W 200W
Manufacturing Process TSMC 28nm TSMC 28nm TSMC 28nm TSMC 28nm
Architecture GCN GCN GCN GCN
Launch Date 06/22/2012 01/09/2012 08/17/2012 01/31/2012
Launch Price $499 $549 $329 $449

Diving right into things, the new 7950 – which we’re going to call the 7950B for lack of a distinct official name – is a performance enhanced part based on the same process that AMD used to create the Radeon HD 7970 GHz Edition. Like the 7970GE, AMD is doing two things here for the 7950B: they’re increasing the base clockspeed, and they’re also introducing their GPU turbo boost functionality to potentially push clockspeeds higher.

With these enhancements the clockspeeds for the 7950B will be 850MHz for the base clock, 925MHz for the boost clock, and the memory clock is kept at 5GHz. As a result the GPU clockspeed difference is anywhere between 50MHz (6%) at its base and 125MHz (16%) at the highest boost clock. Because only the core clock is changing, the performance difference between the 7950 and 7950B will be heavily dependent on whether the game/application at hand is GPU limited; heavily GPU limited tasks (that can stay within the power limits) will benefit the most, while memory bandwidth limited or CPU limited tasks may not benefit at all.

So how is AMD pulling this off? We’ve already covered AMD’s PowerTune Technology With Boost (PT Boost) in depth with the 7970GE review, but in case you missed it, here’s a quick refresher. At its most basic level, PT is a combination of BIOS and Catalyst driver changes that allow AMD to overdrive the GPU when conditions permit. In practice PT Boost is very similar to NVIDIA’s GPU Boost. Both technologies are based around the concept of a base clock (or engine clock in AMD’s terminology) with a set voltage, and then one or more boost bins with an associated voltage that the GPU can move to as power/thermal conditions permit. In essence PT Boost allows suitably equipped cards to overvolt and overclock themselves to a limited degree.

Under the hood, the current incarnation of PT Boost is primarily designed to take advantage of AMD’s previously conservative specifications for the Radeon HD 7950. In implementing their PowerTune technology, AMD opted to base their power consumption calculations around the worst case scenario for leakage, thereby ensuring no card ever exceeded its designated PowerTune limit at an opportunity cost of having not maximized performance. PT Boost effectively inverses this methodology, implementing a Digital Temperate Estimation (DTE) algorithm to determine the real leakage at any given time. By accurately estimating a GPU’s leakage AMD can push the GPU closer to its limits, thereby maximizing its performance. The tradeoff of course is that real power consumption will increase, as AMD’s cards are now eating into what was previously a large power buffer.

Moving on, since PT Boost was designed against AMD’s existing hardware, AMD and their partners have been taking advantage of this design choice by deploying it on existing 7900 series hardware. Just as how the 7970GE was built on existing 7970 board designs, the 7950B specs are intended to be deployed as an upgrade for existing 7950 designs. As with the 7970GE, the real change here is that AMD is qualifying their GPUs to operate at higher voltage/clockspeed combinations. For our converted reference card the new base voltage is 1.125v for 850MHz, up from 1.093v for 800MHz on the original 7950. Meanwhile the boost voltage goes much higher, with AMD using a rather high 1.25v for the 925MHz boost clock. In fact this ends up being the highest voltage a reference Tahiti card operates at, as even the reference 7970GE only used 1.218v.

Radeon HD 7950 Series Voltages
Ref 7970B Base Voltage Ref 7950B Boost Voltage Ref 7950 Base Voltage
1.125v 1.25v 1.093v

These numbers paint an interesting picture, albeit not one that is particularly rosy. For the 7970 AMD was already working with top bin Tahiti GPUs, so to make a 7970GE they just needed to apply a bit more voltage and call it a day. The 7950 on the other hand is largely composed of salvaged GPUs that failed to meet 7970 specifications. GPUs that failed due to damaged units aren’t such a big problem here, but GPUs that failed to meet clockspeed targets are another matter. As a result of the fact that AMD is working with salvaged GPUs, AMD has to apply a lot more voltage to a 7950 to guarantee that those poorly clocking GPUs will correctly hit the 925MHz boost clock.

With that in mind however, all of this appears to be a calculated risk on AMD’s part. The reality of AMD’s situation is that Tahiti can’t compete with GK104’s power efficiency. Tahiti is a clearly superior GPU for compute purposes, but when it comes to gaming AMD and NVIDIA’s best products are virtually tied in performance, a matchup that leaves NVIDIA holding the smaller, lower power GPU. So what is AMD to do in such a situation? If the 7970GE didn’t make it obvious, the 7950B does: forgo all pretense of power efficiency and focus on performance-per-dollar.

With both the 7970GE and 7950B AMD has notably increased their power consumption. We’ll take a look at the numbers in-depth in a bit, but the important change is that based on our data the 7950B is now drawing more power than the GTX 680. This isn’t necessarily a bad tradeoff – after all everyone likes more performance – but like all tradeoffs it does come with consequences. For the 7950B in particular, this means that the TDP has gone up from 200W for the 7950 to 225W for the 7950B.

Launch Details


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  • bennyg - Wednesday, August 15, 2012 - link

    Agree that 7950 is better price/perf than 670. But;

    Reviewers can only review what they have in their rigs. If Nvidia came out with an auto-OC feature and AMD didn't... tough for AMD but hardly "unfair advantage", remember most buyers don't OC, and everyone who bought a 670 has enjoyed their boosted clocks and frames.

    And before you go alleging NV is defrauding reviewers... "surely" you need some kind of evidence that shows retail cards are measurably slower than review cards (which remember are tested in stupidly-beefy-everything-else so the GPU is as unlimited by the rest of the system as possible). Surely everyone reviewing an Intel CPU and getting higher numbers than AMD isn't in Intel's pockets too... maybe the Geforce just "wins" the last 5 months? After AMD sold heaps of well marked up cards for the first 3 months of this year, remember.

    Things like this happening make me glad Apple didn't "invent" and patent the turboboost algorithm </lolapplebashing>
  • prdola0 - Wednesday, August 15, 2012 - link

    Oh come on. Isn't it AMD who is trying desperately to hinder Nvidia's launch with an update which gives only 5% on average, yet it increases consumption by 20W and noise considerably too, and voids warranty if applied to older cards?

    Looking at Steam Survey, it is clear why AMD is so desperate. GTX680 has 0.90% share, while even the 7850 lineup has less, just 0.62%. If you look at the GTX670, it has 0.99%. The HD7970 has only 0.54%, about half of what GTX680 has, which is funny considering that the GTX680 is selling only half the time compared to HD7970. It means that GTX680 is selling 4 times faster.

    You can see that even with the absence of Nvidia's mainstream until tomorrow, Nvidia is outselling AMD massively. And that's why AMD is trying dirty tricks, like promoting 7970Ghz and then not really selling it afterwards, the same with 7750 and now this little bump to 7950, which we might not see in reality as well. Who's to guarantee, that the cards are really comming with AMD's current track record in mind? Noone is. And the poor fella deciding to buy a 7950 would have to be informed well enough not to buy an old 7950 with the old spect and actually be able to tell them apart in a store. Most won't be able to and they won't be getting what they see in the reviews, even though this cheat is just 5%.

  • jabber - Wednesday, August 15, 2012 - link

    AMD/Nvidia are never too worried about total sales of their top of the range cards.

    It's the models below that in the $250-$75 range that pays the wages.

    These cards are the equivalent of the S Class Mercedes. Basically what you find in a S Class today filters down into what we drive in ten years time.

    Tech testers basically. Stuff thats in these cards will be then added into my 8770/9770 in due course.

    Six years ago who would have thought $30 GPUS would have 1GB of ram on them.
  • prdola0 - Wednesday, August 15, 2012 - link

    Well then if Nvidia sells more S-class Mercedes than AMD sells mainstream cars, you could say that AMD is in trouble. No? Reply
  • jabber - Wednesday, August 15, 2012 - link

    So you are saying that Nvidia is selling far more $350 cards than AMD is selling $50-$250 ones?

    Well that would be amazing. Tech news of the century.

    Fact is I've never seen one of these top of the range cards in a PC that I know of AMD or Nvidia while they are being sold.

    I sometimes see them a few years after when they have filtered down via Ebay.

    They sell in very small numbers compared to the rest of the ranges.
  • RussianSensation - Wednesday, August 15, 2012 - link

    That's non-sense. Only 4-5% of cards above $350 comprise the entire sales of a GPU maker. Already shown 100x. Using Steam Hardware survey to compare sales is not accurate. NV didn't even say that Kepler on the desktop gained market share in the latest earnings. They attributed most of their success to Tegra 3 and mobile Kepler contracts. Reply
  • CeriseCogburn - Saturday, August 25, 2012 - link

    Still, the Steam Harware Survey shows your little stupid amd pet getting it's blankity kicked.
    Why so sad ?
  • RussianSensation - Wednesday, August 15, 2012 - link

    HD7970 was 1 month behind but plenty of versions are for sale on Newegg and actually even better than AMD promised:

    - Prices well under $499
    - You still get 3 free games included, which wasn't part of the GE cards

    So essentially that's a faster card than all 680s except for GTX680 Lightning and it costs $30-50 less than the cheapest 680. What's not to like?

    Just because people are buying 4x as many 680s doesn't mean anything. They could be stuck reading reviews from March and haven't seen 7970 GE recapture the performance crown overall and surpass 680 in Dirt 3, SKYRIM, Batman AC, especially with 8AA.
  • CeriseCogburn - Saturday, August 25, 2012 - link

    No one is listening - Steam Survey has proven it - nleat all you want, heck you're still bleating... amd sales SUCK for the card you are promoting....
    Here let me help you amd fanboy out of his mind on failing sales...
    The 660Ti is kicking because it STOMPS the 7870/7850 and barely costs more than 7870 and it matches and beats 7950 plenty of the time and as thejian has shown you in 660Ti thread 24/7/365 for 1920x1200 and ever more 1920x1080, and the 660Ti costs LESS than the 7950...
    nVidia hit the SWEET SPOT - jamming it right in and amd is going down in sales ever more - next Steam Survey.. you'll be WEEPING and cursing the fools for not taking your twisted advice...
    Happy gaming ! :-)
  • CeriseCogburn - Saturday, August 25, 2012 - link

    LOL - " and thats why they did it. Nvidia's cards are auto overclocking, so they were gaining an unfair advantage in "stock" reviews. No more.

    Nvidia started all this with their boost,... "
    Why so sourpuss bill4, amd fanboy much ?
    Look, amd blew it badly on this card - it's a hot core housefire mess.
    My advice for the amd fan - go buy the average/regular 7950 and cross your fingers.
    Of course my real advice is quit being such and idiot and buy the 660Ti at this point.
    I mean that's a no brainer.

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