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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rarson - Friday, September 14, 2012 - link
chizow doesn't understand the concept of early adoption. He only mentioned rebates because that Nvidia rebate debacle has been beaten over his head time and time again.chizow - Friday, September 14, 2012 - link
Ah just a matter of time before the only idiot on the internet willing to defend AMD's laughable 28nm launch prices arrives to defend their honor.How do you feel now about those $550, $450, and $350 pricepoints you so vigorously defended when the 7970/7950/7870 launched?
And yes its important to mention the rebates because revisionists like yourself are so quick to forget the actual rebates, they only mention the price drops.
So just as I asked then, where's AMD's rebates given the floor has completely dropped from under their entire pricing structure just a few months after release, just as I predicted?
Galidou - Sunday, September 16, 2012 - link
We did not vigorously defend the pricing scheme, we're just not seeing it as worse as you can see it, hence why we answer to you. Everytime I see people like you speak about AMD the way they do, I just see so much hate, when you start to say things like idiot and trying to say we're defending our ''honor'' you're past the point where your arguments are worth even a penny to me.If you have to disrespect people when speaking about video cards, there's one thing I have to say, you have a choosen side and it hinders your judgement. Stay respectful and I'll give you credit but now it's too late you just proved ourselves that you're not fit to judge well in this discussion.
Anyone know that a judge couldn't work on an affair of murder if the murdered one is in his own family because it... would severely hinder his judgement by putting emotions in the way. Disrespect to me is the worse form of acting when arguing. You lost it all there to me, I'm just sad I did reply to your previous messages without reading this one first, I would of just realized that it's too late for you.
AMD and Nvidia are both company trying to make money, trying to put one on a pedestal like if everything they do is related to god and thus is perfect... AMD's 4870 was a mistake, 7970 was a mistake, gtx 280 is related to god and it's AMD's pricing scheme that is at fault.
Everything AMD does is wrong, everything Nvidia does wrong is AMD's fault.... Like my 6800 gt that never worked properly with that Nforce 3 chipset, AMD's fault, that driver release that fried tons of Nvidia's video cards, AMD's fault, GTX 670's performance so close to GTX 680's performance, AMD's fault, 660 ti 192 bit bus and 24 ROPs, AMD's fault(I heard they stole them during the night and are not willing to give em back unless Nvidia pays a heavy ransom), Why isn't Nvidia making more money than Intel and Microsoft, AMD's fault, my grandfather's cancer, AMD's fault, wow, life is a bag full of surprise. Chozow's lack of respect calling us stupid, AMD's fault, we lost our honor because of... AMD's fault.....
chizow - Sunday, September 16, 2012 - link
Uh disrespect? You mean like you questioning very easily referenced facts like price and performance at every turn, or questioning how much I paid for a 2xGTX 670 or even that they existed with 680 PCB? Or questioning numbers only to be rebuked by a link from a widely respected website, only to question that website, then get provided with more benchmarks from one of the site you linked and question that one too?There comes a point you can't reason with people like you, so if you want to argue about emotional attachment leading to irrational behavior, you should really look in the mirror.
But what should I care, as you said everyone must look themselves in the mirror and be at peace with their own decisions in life, I can for a fact say I'm good with my buying decision this round, do you think one can say the same about buying AMD 28nm parts under their ridiculous asking prices, especially given all of the recent price drops?
Also, I have been critical of Nvidia as well with 28nm, so to say I think they can do no wrong, downright dishonest on your part. There's a reason I waited to buy my 670s instead of snatching them up at launch for $400, but then again, I've been at this long enough to make an informed decision.
Galidou - Sunday, September 16, 2012 - link
''Uh disrespect? You mean like you questioning very easily referenced facts like price and performance at every turn, or questioning how much I paid for a 2xGTX 670 or even that they existed with 680 PCB''Nope, I mean calling other idiots: ''Ah just a matter of time before the only idiot on the internet willing to defend AMD's laughable 28nm launch prices arrives to defend their honor.''
End of the discussion, you're a disrespectful Nvidia fanboy, I doubted for the gtx 670 price you said because I was vigorously looking for a 670 but not a reference fan design, something with an aftermarket fan that will stay cool for a nice and quiet overclock.
For what you call facts, life turn around perception and interpreted by the brain. Women tend to dislike when their boyfriend cheat on them while in some country it's normal to have many wifes, know what I mean? Perception is something personnal, something might be bad and abnormal and seem like a fact from someone's standpoint but for another human being, it might be just normal dependnig on their choosen side, past experiences and emotions. If someone totally beleives 2+2 makes 5 and no one can convince him of anything else, then to him it's the truth. If the only truth to you is your truth, you will disagree all of your life with other peoples because they have a different point of view.
All I was discussing with you isn't that AMD is perfect and that their pricing is perfect, I was just defending my point of view, the way I saw things while saying ''TO ME IT SEEMS LOGICAL'' while all you had to say was ''REFERENCED FACTS, FACTS, FACTS, FACTS'' not caring about how I perceived things, I just hoped you could understand why I see things this way, I understand the way you see things because I can tell it seems logical to me but that isn't the way I see IT.
chizow - Monday, September 17, 2012 - link
"End of the discussion, you're a disrespectful Nvidia fanboy."Please don't talk about respect when you can't even adhere to your own standards.
If you claim "TO ME SEEMS LOGICAL" while questioning my conclusions but ignoring facts and historical data that are relevant to the industry in general and graphics cards in particular, that suggests to me that your thought processes are not logical at all, but born of ignorance or subnormal intelligence.
After all, a simpleton can believe Unicorns and Fairies exist, but that does not make it so.
You brought up the GTX 280 again, yet once again you can't seem to understand the very key differences with the GTX 280 vs. 7970 launch prices. I've already outlined them, do I need to do so again?
Simple question, do you think Nvidia's pricing was worst at launch with the 280 than AMD's pricing with the 7970?
Galidou - Monday, September 17, 2012 - link
''You brought up the GTX 280 again, yet once again you can't seem to understand the very key differences with the GTX 280 vs. 7970 launch prices. I've already outlined them, do I need to do so again?''I brought that up?? You have to read back to realize you started it all again speaking of rebates and such which was the only reason why I answered to you to show that not everyone sees the way you do.
Maybe we could just state that Nvidia made a mistake by pricing the gtx 680 at 500$ because it was stronger than a 600$ card and then they are the faulty one as you usually see things.
''I've already outlined them, do I need to do so again?''
Well if you outlined them, if it was so different, why did you bring up the apst of the gtx 280 to compare to this different story in the first place?
Calling you an Nvidia fanboy isn'T disrespectful to me like calling other idiots defending their honor. It means you have a choosen side, maybe it might seem like it's an attack but it'S not, sorry if the hat fits your head.
Galidou - Monday, September 17, 2012 - link
Oh and I was wondering, for someone so informed about your purchases and everything, did you say you owned a gtx 280? For someone buying 330$ gtx 670 that's quite a fun ''fact'' considering you whined about the TOO LOW price of the radeon 4870, but no, you didn't get to buy one of those for 250$ on special, you got the gtx 280.... Fun stuff when the 4850/4870 were at the TOP of Performance/dollar charts, which was something we don't see often.....(fanboyism?)I'm an informed buyer which is why the only video cards I bought brand new at launch for me, my wife or friends are: Geforce ti 4200, radeon hd 9500 flashed to 9700 pro, 8800 gt, radeon 4850/4870, gtx 460 ti, radeon 6850/6870, gtx 660 ti and the radeon 7950 I super overclocked for my 3 monitors and skyrim :)
And yes there are ATI cards included in my buying decision which doesn't make me a Fanboy and helps my OPINION being undistorted by emotions thus the reason I'm not calling others idiots when speaking in forums related to VIDEO CARDS.
Galidou - Monday, September 17, 2012 - link
''And yes there are ATI cards included in my buying decision''I meant Nvidia cards :)
chizow - Monday, September 17, 2012 - link
Since you love to make this about me, when it really isn't....Yes I bought a GTX 280 at launch but I waited a few days and got lucky on a Bing cash back promotion on Ebay. 35% Bing Cash Back, quite a few others got it as well (feel free to google it), brought the total to $420ish. Then Nvidia issued their big rebate after the 4870 launch, so I had the option of $120 check or $150 EVGA bucks, I took the cash.
So $300, minus the $220 I got for my 8800GTX on Ebay and I paid a whopping total of $80 out of pocket for the fastest single GPU. Early 2009 I got a 2nd 280 for $230 in a Dell deal after the economic crash that dropped prices on all GPUs....
Obviously not everyone would have been so fortunate, but if I didn't get 280s, I might very well have gotten 260s or waited for 285s.