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GeForce GTX 660: Introducing GK106

Nvidia GeForce GTX 650 And 660 Review: Kepler At $110 And $230
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Yesterday, there were five GeForce cards in the channel based on Nvidia's Kepler architecture. Four of them centered on the company's GK104 graphics processor. One, the GeForce GT 640, employs a derivative GPU called GK107. Now, we have a second board with GK107 as its foundation.

But the second card surfacing today features an all-new Kepler-based chip called GK106.

GK106 is composed of five SMX clusters, each with 192 CUDA cores totaling 960. Sixteen texture units per SMX give us a total of 80 across the GPU. And three ROP clusters able to process eight full-color pixels yield 24 per clock cycle. A trio of 64-bit memory controllers aggregate into a 192-bit memory interface.

Nvidia claims that its GK106 is a fully-utilized GPU, and that there aren't any disabled resources we might see flipped on later. We find this odd, given that one SMB cluster standing on its own to the side.

Like the GeForce GTX 660 Ti, the reference 660 includes 2 GB of memory. The only way Nvidia is able to achieve this using three 64-bit memory controllers is by mixing capacities. Also like the 660 Ti, the only way this amount of memory can be handled over a 192-bit bus is with mixed-density ICs. It works like this: the three 64-bit controllers divide the total memory into 512 MB chunks, which are accessed at the full 192 bits. The remaining 512 MB is addressed by just one 64-bit controller in a completely separate transaction. Nvidia won't divulge anything else about its implementation for competitive reasons, but there is undoubtedly latency there the controllers have to contend with.

This is something we drill down into using bandwidth-specific benchmarks, and you'll want to keep it in mind in games where that extra 512 MB is utilized.


GeForce GTX 660 TiGeForce GTX 660
GeForce GTX 570
Radeon HD 7850
Radeon HD 7870
Shader Cores
1344960
480
1024
1280
Texture Units
11280
60
64
80
Color ROPs
2424
48
32
32
Fabrication Process
28 nm
28 nm40 nm
28 nm28 nm
Core (Shader)/Boost Clock915/980 MHz980/1033 MHz
732 (1464) MHz
860 MHz
1000 MHz
Memory Clock
1502 MHz GDDR51502 MHz GDDR5950 MHz GDDR5
1200 MHz GDDR51200 MHz GDDR5
Memory Bus
192-bit192-bit
320-bit
256-bit256-bit
Memory Bandwidth144.2 GB/s144.2 GB/s
152 GB/s
153.6 GB/s153.6 GB/s
Graphics RAM
2 GB GDDR52 GB GDDR51.25 GB GDDR5
2 GB GDDR52 GB GDDR5
Power Connectors
2 x 6-pin1 x 6-pin2 x 6-pin1 x 6-pin2 x 6-pin
Maximum Thermal
Design Power
150 W140 W
219 W
130 W
175 W
Price
$300-$340
(Newegg)
$230
(MSRP)
$240-$330
(Newegg)
$200-$245
(Newegg)
$260-$370
(Newegg)


Given identical memory specifications, the GeForce GTX 660 Ti and 660 offer the same 144.2 GB/s of memory bandwidth. Most of the 660's other specs are less aggressive, though: CUDA cores, texture units, and ROPs are cut by roughly 30% in comparison. Nvidia helps overcome some of the impact of fewer resources by juicing the core and average GPU Boost frequencies, though.

Reference GeForce GTX 660

At first glance, Nvidia's reference GeForce GTX 660 reminds us of a GeForce GTX 460 or even the Radeon HD 7850. But then we turn it over...

...and the PCB only covers about 75% of the card's length. The overhang comes from the fan and shroud, suggesting that vendors can make much smaller versions of the GeForce GTX 660, providing they're able to address cooling effectively. Zotac sent us a sample of its card proving this is a feasible endeavor.

Again, Nvidia's reference card comes with 2 GB of GDDR5 at 1502 MHz. Its base core clock is 980 MHz, while GPU Boost averages 1033 MHz.

The reference GeForce GTX 660 exposes two dual-link DVI ports, calls for two DL-DVI, one HDMI port, and a DisplayPort output. This matches the GeForce GTX 660 Ti, and both cards support up to four monitors operating concurrently with three in Surround mode.

Nvidia's reference PCB measures 7" x 4.5", which is fairly small for a performance/mainstream card. One six-pin auxiliary power connector supplements the PCI Express slot's 75 W delivery, satisfying a TDP that stretches up to 140 W. A single SLI connector is tell-tale: the GeForce GTX 660 only supports dual-card configurations.

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Top Comments
  • 29 Hide
    lahawzel , September 13, 2012 2:23 PM
    Goddamn Mike NY Gmail or whatever the hell your name is supposed to be, here, proper commenting etiquette:

    1. Read the article.
    2. Understand what the article is talking about.
    3. If you find an urge to comment about "______ sucks" or "_______ wins again", especially when the article says the opposite of what you want to post, chances are your comment will look dumb as hell when it's posted and earn you 20 downvotes. Therefore, don't post that goddamn poor excuse of a "comment".
  • 26 Hide
    Anonymous , September 13, 2012 2:30 PM
    Why are there giant gaps in both lineups? AMD has the 7770 at $130 and 7850 at $230 -- nvidia has the 650 and 660 at similar price points -- ideally for my budget would be something in the $150-170 price range, but I either have to compromise or shell out more. It seems like an obvious market gap.
  • 25 Hide
    EzioAs , September 13, 2012 2:31 PM
    Nice article to be honest. I'm really glad you tested the Radeon cards with the new driver compared to other review sites.

    I've got nothing else to say on the GTX650 but to just point out that it's a weak card.

    On the other hand, the GTX660 is probably the only Kepler (besides the 670) that impresses me. I don't know about everyone else though. To point out one thing, most Radeon 7870s can be found at $240 or lower without MIR. The GTX660 is priced well for a release MSRP and makes the 660ti offers less value, kind of like the 670 vs 680. For 8xMSAA, the performance does cripple but I think at this price point, most people are going to stay with 4xAA or possibly lower.
Other Comments
  • 21 Hide
    EDVINASM , September 13, 2012 1:35 PM
    Was waiting for GTX 650 to see if it can beat the old GTX 550 Ti but it seems other than power draw it's no match. Might as well keep my GPU until next NVidia lineup. GTX 660 on other hand is only €50 cheaper than GTX 660 Ti meaning its a no budget saver to buy non Ti version. Fail...
  • 29 Hide
    lahawzel , September 13, 2012 2:23 PM
    Goddamn Mike NY Gmail or whatever the hell your name is supposed to be, here, proper commenting etiquette:

    1. Read the article.
    2. Understand what the article is talking about.
    3. If you find an urge to comment about "______ sucks" or "_______ wins again", especially when the article says the opposite of what you want to post, chances are your comment will look dumb as hell when it's posted and earn you 20 downvotes. Therefore, don't post that goddamn poor excuse of a "comment".
  • 26 Hide
    Anonymous , September 13, 2012 2:30 PM
    Why are there giant gaps in both lineups? AMD has the 7770 at $130 and 7850 at $230 -- nvidia has the 650 and 660 at similar price points -- ideally for my budget would be something in the $150-170 price range, but I either have to compromise or shell out more. It seems like an obvious market gap.
  • 25 Hide
    EzioAs , September 13, 2012 2:31 PM
    Nice article to be honest. I'm really glad you tested the Radeon cards with the new driver compared to other review sites.

    I've got nothing else to say on the GTX650 but to just point out that it's a weak card.

    On the other hand, the GTX660 is probably the only Kepler (besides the 670) that impresses me. I don't know about everyone else though. To point out one thing, most Radeon 7870s can be found at $240 or lower without MIR. The GTX660 is priced well for a release MSRP and makes the 660ti offers less value, kind of like the 670 vs 680. For 8xMSAA, the performance does cripple but I think at this price point, most people are going to stay with 4xAA or possibly lower.
  • 11 Hide
    EzioAs , September 13, 2012 2:37 PM
    Quote:
    Why are there giant gaps in both lineups? AMD has the 7770 at $130 and 7850 at $230 -- nvidia has the 650 and 660 at similar price points -- ideally for my budget would be something in the $150-170 price range, but I either have to compromise or shell out more. It seems like an obvious market gap.


    The 6870 might be more compelling at that price point. Newegg still sells them. It's too bad that AMD didn't release a 7830 or something similar from the Nvidia side. But chances are, you probably can get the 7850 or 660 below $200 by the end of the year. Fingers cross though.
  • 7 Hide
    tomfreak , September 13, 2012 2:37 PM
    mikenygmailThanks for the attempted compliment, but call me Mike. I'm glad you've been paying attention.It was more of a joke than anything else to simply write "AMD wins again!" and it was actually pretty funny! I try to balance things out so that no one company is viewed too favorably.For example, I recently bought an Nvidia GTX 460 1 GB 256 bit card for $70, new, with a 3 month warranty for a friend to upgrade his gaming computer. Unusual? Yes. Great deal? You better believe it! Of course, if an equivalent AMD card was available at a cheaper price, that's the one I would've bought.Now, relax and try to control yourself. Refrain from the use of profanity in future posts. Thanks.
    they cant even dare to put up a weaker 460SE up against 650 let alone a full 460. I guessing the 650 got trash hard when u put serious shader and resolution on it. It is a garbage card @ $110.
  • 12 Hide
    EzioAs , September 13, 2012 2:38 PM
    Quote:
    Gtx 660 is the only option in mid-range gpu


    That is if you don't need the compute performance in which AMD clearly leads
  • 15 Hide
    Anonymous , September 13, 2012 2:39 PM
    I totally agree with TomFreak

    another thing, i would prefer more comparison to old cards like the 460 1GB (256bit). i am sure alot of gamers still use that old card
  • 12 Hide
    jimbaladin , September 13, 2012 2:39 PM
    Buy a 7850, overclock it. Win.
  • 20 Hide
    cleeve , September 13, 2012 2:48 PM
    TomfreakHow "nice" of u tomshardware. By only compared 7750/7770 vs 650 in high detail but not comparing 7750/7770 on the Ultra detail, then when u pull out a 460 SE/9800GT for benchmark, u are taking away 650(why?). Is it because 650 performance is too poor to show off on benchmark? It doesnt take a genius to figure out the huge diff between 6870 vs 650. 7770= 6850 speed. So I guess even the 7750/460SE are putting shame on 650 on those high quality detail? too shy to show off 460SE/9800GT up against 650?I dare u put on a detailed benchmark with 650 up against 7770/7750/GTS450/550ti/460/9800GT/9800GTX on all condition. Not a selective benchmark.


    Dude, we included the 650 for reference at high details in the rest of the benchmarks. The info is there, just trying to keep it focused.

    It's all there. Just look for it.

    Tomfreak I guessing the 650 got trash hard when u put serious shader and resolution on it.


    It did, look at the numbers from the other high detail benches. The 460 kills it.

    But the 460 192-bit is too expensive for a direct comparison, so I didn't include it in the standard low-detail benches. It has a higher price point than the 7770.
  • 21 Hide
    Gman450 , September 13, 2012 2:55 PM
    NVIDIA seriously needs to step up their mid range cards! The 650 is weaker than expected...
  • 21 Hide
    EzioAs , September 13, 2012 3:01 PM
    Quote:
    NVIDIA seriously needs to step up their mid range cards! The 650 is weaker than expected...


    True. I thought it could at least give the 7770 some competition, but as it turns out it's slower than the 7750. But actually, that's to be expected since it's basically a GT640 with GDDR5. They should probably called it a GT645 or GTS640. It doesn't deserve the GTX name
  • 5 Hide
    tomfreak , September 13, 2012 3:09 PM
    CleeveDude, we included the 650 for reference at high details in the rest of the benchmarks. The info is there, just trying to keep it focused.It's all there. Just look for it.It did, look at the numbers from the other high detail benches.
    according to the bench, each game have 2 presets, the similar priced 7770/7750 is missing on the second higher bench on most games. Would be love the 6870 being replace with 7770/7750 on the second game bench.
  • 5 Hide
    bawchicawawa , September 13, 2012 3:13 PM
    WHY didn't they add the 7770 to the 1920 x 1080 preset? =\
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