The NVIDIA GeForce GTX 660 Review: GK106 Fills Out The Kepler Family
by Ryan Smith on September 13, 2012 9:00 AM ESTAs our regular readers are well aware, NVIDIA’s 28nm supply constraints have proven to be a constant thorn in the side of the company. Since Q2 the message in financial statements has been clear: NVIDIA could be selling more GPUs if they had access to more 28nm capacity. As a result of this capacity constraint they have had to prioritize the high-profit mainstream mobile and high-end desktop markets above other consumer markets, leaving holes in their product lineups. In the intervening time they have launched products like the GK104-based GeForce GTX 660 Ti to help bridge that gap, but even that still left a hole between $100 and $300.
Now nearly 6 months after the launch of the first Kepler GPUs – and 9 months after the launch of the first 28nm GPUs – NVIDIA’s situation has finally improved to the point where they can finish filling out the first iteration of the Kepler GPU family. With GK104 at the high-end and GK107 at the low-end, the task of filling out the middle falls to NVIDIA’s latest GPU: GK106.
As given away by the model number, GK106 is designed to fit in between GK104 and GK107. GK106 offers a more modest collection of functional blocks in exchange for a smaller die size and lower power consumption, making it a perfect fit for NVIDIA’s mainstream desktop products. Even so, we have to admit that until a month ago we weren’t quite sure whether there would even be a GK106 since NVIDIA has covered so much of their typical product lineup with GK104 and GK107, leaving open the possibility of using those GPUs to also cover the rest. So the arrival of GK106 comes as a pleasant surprise amidst what for the last 6 months has been a very small GPU family.
GK106’s launch vehicle will be the GeForce GTX 660, the central member of NVIDIA’s mainstream video card lineup. GTX 660 is designed to come in between GTX 660 Ti and GTX 650 (also launching today), bringing Kepler and its improved performance down to the same $230 price range that the GTX 460 launched at nearly two years ago. NVIDIA has had a tremendous amount of success with the GTX 560 and GTX 460 families, so they’re looking to maintain this momentum with the GTX 660.
| GTX 660 Ti | GTX 660 | GTX 650 | GT 640 | |
| Stream Processors | 1344 | 960 | 384 | 384 |
| Texture Units | 112 | 80 | 32 | 32 |
| ROPs | 24 | 24 | 16 | 16 |
| Core Clock | 915MHz | 980MHz | 1058MHz | 900MHz |
| Shader Clock | N/A | N/A | N/A | N/A |
| Boost Clock | 980MHz | 1033MHz | N/A | N/A |
| Memory Clock | 6.008GHz GDDR5 | 6.008GHz GDDR5 | 5GHz GDDR5 | 1.782GHz DDR3 |
| Memory Bus Width | 192-bit | 192-bit | 128-bit | 128-bit |
| VRAM | 2GB | 2GB | 1GB/2GB | 2GB |
| FP64 | 1/24 FP32 | 1/24 FP32 | 1/24 FP32 | 1/24 FP32 |
| TDP | 150W | 140W | 64W | 65W |
| GPU | GK104 | GK106 | GK107 | GK107 |
| Transistor Count | 3.5B | 2.54B | 1.3B | 1.3B |
| Manufacturing Process | TSMC 28nm | TSMC 28nm | TSMC 28nm | TSMC 28nm |
| Launch Price | $299 | $229 | $109 | $99 |
Diving right into the guts of things, the GeForce GTX 660 will be utilizing a fully enabled GK106 GPU. A fully enabled GK106 in turn is composed of 5 SMXes – arranged in an asymmetric 3 GPC configuration – along with 24 ROPs, 3 64bit memory controllers, and 384KB of L2 cache. Design-wise this basically splits the difference between the 8 SMX + 32 ROP GK104 and the 2 SMX + 16 ROP GK107. This also means that GTX 660 ends up looking a great deal like a GTX 660 Ti with fewer SMXes.
Meanwhile the reduction in functional units has had the expected impact on die size and transistor count, with GK106 packing 2.54B transistors into 214mm2. This also means that GK106 is only 2mm2 larger than AMD’s Pitcairn GPU, which sets up a very obvious product showdown.
In breaking down GK106, it’s interesting to note that this is the first time since 2008’s G9x family of GPUs that NVIDIA’s consumer GPU has had this level of consistency. The 200 series was split between 3 different architectures (G9x, GT200, and GT21x), and the 400/500 series was split between Big Fermi (GF1x0) and Little Fermi (GF1x4/1x6/1x8). The 600 series on the other hand is architecturally consistent from top to bottom in all respects, which is why NVIDIA’s split of the GTX 660 series between GK104 and GK106 makes no practical difference. As a result GK104, GK106, and GK107 all offer the same Kepler family features – such as the NVENC hardware H.264 encoder, VP5 video decoder, FastHDMI support, TXAA anti-aliasing, and PCIe 3.0 connectivity – with only the number of functional units differing.
As GK106’s launch vehicle, GTX 660 will be the highest performing implementation of GK106 that we expect to see. NVIDIA is setting the reference clocks for the GTX 660 at 980MHz for the core and 6GHz for the memory, the second to only the GTX 680 in core clockspeed and still the same common 6GHz memory clockspeed we’ve seen across all of NVIDIA’s GDDR5 desktop Kepler parts this far. Compared to GTX 660 Ti this means that on paper GTX 660 has around 76% of the shading and texturing performance of the GTX 660 Ti, 80% of the rasterization performance, 100% of the memory bandwidth, and a full 107% of the ROP performance.
These figures mean that the performance of the GTX 660 relative to the GTX 660 Ti is going to be heavily dependent on shading and rasterization. Shader-heavy games will suffer the most while memory bandwidth-bound and ROP-bound games are likely to perform very similarly between the two video cards. Interestingly enough this is effectively opposite the difference between the GTX 670 and GTX 660 Ti, where the differences between the two of those cards were all in memory bandwidth and ROPs. So in scenarios where GTX 660 Ti’s configuration exacerbated GK104’s memory bandwidth limitations GTX 660 should emerge relatively unscathed.
On the power front, GTX 660 has power target of 115W with a TDP of 140W. Once again drawing a GTX 660 Ti comparison, this puts the TDP of the GTX 660 at only 10W lower than its larger sibling, but the power target is a full 19W lower. In practice power consumption on the GTX 600 series has been much more closely tracking the power target than it has the TDP, so as we’ll see the GTX 660 is often pulling 20W+ less than the GTX 660 Ti. This lower level of power consumption also means that the GTX 660 is the first GTX 600 product to only require 1 supplementary PCIe power connection.
Moving on, for today’s launch NVIDIA is once again going all virtual, with partners being left to their own designs. However given that this is the first GK106 part and that partners have had relatively little time with the GPU, in practice partners are using NVIDIA’s PCB designs with their own coolers – many of which have been lifted from their GTX 660 Ti designs – meaning that all of the cards being launched today are merely semi-custom as opposed to some fully custom designs like we saw with the GTX 660 Ti. This means that though there’s going to be a wide range designs with respect to cooling, all of today’s launch cards will be extremely consistent with regard to clockspeeds and power delivery.
Like the GTX 660 Ti launch, partners have the option of going with either 2GB or 3GB of RAM, with the former once more taking advantage of NVIDIA’s asymmetrical memory controller functionality. For partners that do offer cards in both memory capacities we’re expecting most partners to charge $30-$40 more for the extra 1GB of RAM.
NVIDIA has set the MSRP on the GTX 660 at $229, which NVIDIA’s partners will be adhering to almost to a fault. Of the 3 cards we’re looking at in our upcoming companion GTX 660 launch roundup article, every last card is going for $229 despite the fact that every last card is also factory overclocked. Because NVIDIA does not provide an exhaustive list of cards and prices it’s not possible to say for sure just what the retail market will look like ahead of time, but at this point it looks like most $229 cards will be shipping with some kind of factory overclock. This is very similar to how the GTX 560 launch played out, though if it parallels the GTX 560 launch close enough then reference-clocked cards will still be plentiful in time.
At $229 the GTX 660 is going to be coming in just under AMD’s Radeon HD 7870. AMD’s official MSRP on the 7870 is $249, but at this point in time the 7870 is commonly available for $10 cheaper at $239 after rebate. Meanwhile the 2GB 7850 will be boxing in the GTX 660 in from the other side, with the 7850 regularly found at $199. Like we saw with the GTX 660 Ti launch, these prices are no mistake by AMD, with AMD once again having preemptively cut prices so that NVIDIA doesn’t undercut them at launch. It’s also worth noting that NVIDIA will not be extending their Borderlands 2 promotion to the GTX 660, so this is $229 without any bundled games, whereas AMD’s Sleeping Dogs promotion is still active for the 7870.
Finally, along with the GTX 660 the GK107-based GTX 650 is also launching today at $109. For the full details of that launch please see our GTX 650 companion article. Supplies of both cards are expected to be plentiful.
| Summer 2012 GPU Pricing Comparison | |||||
| AMD | Price | NVIDIA | |||
| Radeon HD 7950 | $329 | ||||
| $299 | GeForce GTX 660 Ti | ||||
| Radeon HD 7870 | $239 | ||||
| $229 | GeForce GTX 660 | ||||
| Radeon HD 7850 | $199 | ||||
| Radeon HD 7770 | $109 | GeForce GTX 650 | |||
| Radeon HD 7750 | $99 | GeForce GT 640 | |||
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chrnochime - Thursday, September 13, 2012 - link
You mean that they spun the results in NV's favor when the 670 came out, and then again in AMD's favor when comparing OC results from 7950 against 660TI OC and 670 OC?chizow - Thursday, September 13, 2012 - link
Is AMD going to issue rebates for the 7870? $150 price drop in 4 months is pretty sad beans for all the AMD early adopters.RussianSensation - Thursday, September 13, 2012 - link
No, because if you want the latest tech on latest 28nm, you understand you are paying a premium for it. If not, you sit out for 6-7 months and wait for more price drops. This is how it always worked. I am sure early AMD adopters don't care since their cards already paid for most of their cost with bitcoin mining on the side and they have enjoyed a cool and efficient card for 7 months. How are your 680s doing that you dropped $1k on?Care to remind everyone that GTX280 launched at $649 on June 16, 2008, dropped $150 1 month immediately when 4870 launched and then 9.5 months later AMD delivered a $269 HD4890 that offered similar performance.
I guess in that generation the early adopter lost $380 by going with the 280 in just 9.5 months but you failed to mention that's how it works in the GPU industry.
chizow - Thursday, September 13, 2012 - link
Except we already knew the 7870 wasn't worth the asking price when it was released, so the natural response would've been to wait by those who already knew price drops were imminent on grossly inflated 28nm parts.And I guess you already forgot, Nvidia did right by its early adopting customers by issuing $100-$150 rebates to those who bought a GTX 260 or 280 before the price drops, which is why I asked. Same reason I asked if AMD was going to do the same if and when Nvidia adjusted the pricing landscape with Kepler to force cuts across the board for AMD's ridiculous pricing structure. So again, where are AMD's rebates given every 28nm part they released is worth roughly 30-40% less than original MSRP? That's more than even your referenced drops on the GTX 260/280.
4890 was nothing special, Nvidia released an equivalent GTX 275 for similar price and those prices were due largely to price wars in the midst of a massive global recession.
As for my $1K GTX 680s, they don't exist because I wouldn't pay that much for such a small increase in generational performance on a midrange ASIC, I paid $660 for 2x GTX 670 on 680 PCBs instead which is probably still a bit more than I think they are worth, but I figure after the 2x Borderlands promos they are much closer to the $300 price point a 2nd tier GK104 SKU should have been sold at anyways. :D
rarson - Friday, September 14, 2012 - link
"Except we already knew the 7870 wasn't worth the asking price when it was released"So the people who "knew" this weren't buying it anyway, and hence do not need a rebate. You really should read what you write before posting your comment.
Here's how technology works, dude: new technology is expensive. As time goes on, it becomes cheaper as more people start adopting it. The 7870 really was worth the price when it came out (no shit, it really was). You can figure this out by seeing that people actually went and bought them. Supply was constrained and the process was very expensive (more so than previous process shrinks) so even just getting the wafers allocated was tougher than before. On top of that, AMD had to adjust their pricing to deal with the constrained supply. Price it too low, and whatever stock that you have sells out too quickly and you sit for months with no stock on the shelf, selling nothing (just ask Nvidia).
I know, I know, you can't grasp basic economics. I'm wasting my breath. Maybe once you move out of the basement you'll figure out how the real world works.
chizow - Friday, September 14, 2012 - link
Yeah it was a rhetorical question, I know AMD isn't issuing rebates, they don't have the money to return they'd just be borrowing more from Abu Dhabi to cut that check that might very well bounce.As for how technology works, you once again demonstrate how little you know about the industry. Prices drop, like the GTX 580/570 and 6970/6950 that held their prices for a good full 20 months before the launch of 28nm parts? And even after the launch of 28nm, they still held their prices because there was no incentive or need to drop in price based on relative price and performance?
You have no idea what you're talking about, stop typing. Parts lose their value and drop in price when a new part forces that change. Usually this happens when a new generation of product or a new process/fabrication node forces the change by introducing a dramatic increase in price:performance. In this case, the prices drops are being forced by products that are the *SAME* process and relative generation (from Nvidia).
What this *SHOULD* tell you is that the 28nm offerings from AMD were grossly overpriced and offered FAR less improvement for the asking price, but these simple concepts obviously escape you.
Galidou - Saturday, September 15, 2012 - link
660$ for 2 gtx 670 on 680 pcbs, you got engineer samples? I've been looking on ebay for USED 670 and the best price one ended was 355$ with shipping and that was without the borderlands 2 coupon. I've seen some reference cards going down to 344$ before taxes and after 20$ mail in rebate(around 380$ shipped) but they were FAR from 680 PCBs.I'd really like to see those 670's at 330$ with 680 PCB's, would really like.....
One comment about the rebate on the gtx 280, it's quite different from now. The 549$ radeon 7970 lost to a 499$ gtx 680 3 months after it's launch.
The 650$ gtx 280 was on average 10% better and sometimes 10% worse than the 300$ radeon 4870 one month after it's launch...
chizow - Saturday, September 15, 2012 - link
Hi Galidou, you're not here to defend AMD's launch prices again too are you?670 on 680 PCBs are quite commonplace, maybe you've heard of the EVGA FTW versions? Galaxy has a similar one with their GC parts, no engineering samples needed:
http://forums.anandtech.com/showthread.php?t=22660...
http://www.newegg.com/Product/Product.aspx?Item=N8...
Please feel free to check the reviews on Newegg link, you will see I'm a verified owner. ;)
As for the GTX 280, once again more revisionist history from the usual suspects. GTX 280 was closer to 15-20% faster especially at high resolutions with AA due to the 1GB VRAM compared to the 4870's 512MB. The gap widens even further if you look at later reviews.
http://www.computerbase.de/artikel/grafikkarten/20...
Only after the 1GB 4870 and 4890 releases months later did this change so the price difference even after the $150 price cut to $500 was still justifiable. I still have a GTX 280 as a backup card and it still runs modern games great, a 512MB 4870 would barely be able to handle the default frame buffer....
Secondly, GTX 280's asking price was reasonable compared to last-gen parts, unlike AMD's 28nm parts, as it offered 2x the performance of the 8800/9800GTX, more performance than the 9800GX2 or 3870X2, and almost tripled the performance of AMD's fastest single GPU, the 3870. What Nvidia did not account for was both AMD's return to competitiveness with the RV770 *AND* their massive undercut on pricing simultaneously.
Lastly, of course, is Nvidia actually did right by their customers by issuing those rebates, which is just good business to ensure they took care of their most enthusiastic customers. Certainly more than we can say for AMD though. AMD may have made some short-term profit, but at what cost? They certainly have more than a few fans who are going to be outraged by the massive cuts so soon after launch.
Galidou - Saturday, September 15, 2012 - link
I just removed the 4870 512mb I had and it still runs perfectly but my wife used it on a 1680*1050 monitor. The 280 took advantage at 2560*1600, but you can imagine it was mainly for benchmark purposes. Not a lot of people do use this resolution NOW so imagine 4 years ago... let's say >0,05% back in 2008(most of them being artists and not gamers), considering the cost of one of those monitors... yep you guessed it, about the price of 2 gtx 280 at launch, for ONE monitor.... The price of my whole computer with the 4870 back in 2008...''Secondly, GTX 280's asking price was reasonable compared to last-gen parts, unlike AMD's 28nm parts, as it offered 2x the performance of the 8800/9800GTX''
When AMD fanboys said the 7970 was priced rightly compared to last gen parts(which it was, there was no bargain for sure but it was 40% higher price for 70% more perf) Nvidia fanboys said: You gotta be freaking kidding me, are you blind, ffs remove your red glasses and wake up''.
''Hi Galidou, you're not here to defend AMD's launch prices again too are you?''
Not necessarily but it seems you are here to attack them again. A 550$ card loses in 65% of the games to a 500$ card 3 months after it's launch(radeon 7970 vs gtx 680)....a 650$ card is 10% faster than a 300$ card in 60% of the games one month after it's launch(gtx 280 vs 4870). My reflections above seemed logical to me, I guess life is a question of perception.
Galidou - Saturday, September 15, 2012 - link
I think there's one thing we should say about pricing mistakes and rebate. A gamer buying an i7 980x 1 week prior to the sandy bridge launch, and I know it happened... poor them...Nice link on the German website, you must of looked a lot of websites to find a 20% advantage on average for a gtx 280 because tom hardware, techpowerup and anandtech shows it average 10% faster but nice finding you got there. If only I could read German. And we both know the websites I named above are certainly more highly regarded than computerbase.de..........
And good job, because I'm really looking forward to change the gtx 660 ti I got for my wife for a gtx 670 but the best I could get to is either 355$ USED(an auction, not a buy it now) on ebay or 344$ before taxes and after mail in rebate(hate those I'm usually not even using them because they use your information to harass your life). But I guess it's possible to find them at 330$ after mail in rebate and before taxes but in the end it's closer to the 400$ mark than the 300$ mark.