GTX 660M vs GT 650M GDDR5 – isn’t it the same?

(GTX 660M dealsGT 650M deals and best deals)


I suggest that you read the GT 650M GDDR5 vs GT 650M DDR3 revised article – it reveals more details about the GTX 660M and GT 650M GDDR5 and DDR3 models.



So, Kepler is out and brings some interesting cards to the mobile gaming world. The GT 650M and GTX 660M are two of the most interesting cards from the Kepler series. Unlike the GTX 670M and GTX 675M, the GTX 660M are real Kepler core based cards. The GT 660M offers almost the same power as the previous generation GTX 570M and not much less performance from the GTX 670M (See here GTX 660M vs GTX 670M performance article). The GT 650M is based on the same chip actually and have two version currently, the GDDR5@1000MHZ version and the DDR3@900MHZ version. Ofcouse, card makers can decide to set other clocks to their cards.


Lets take a look in this GT 650M and GT 660M simple table:

Model Core, shaders (vertex / geometry / pixel) memory and bandwidth Core speed
GTX 660M GDDR5 Kepler (GK107), 384 unified : 32 : 16, 28nm process GDDR5@1000MHZ-1250MHZ,  64GB/s 835MHZ
GT 650M GDDR5 Kepler (GK107), 384 unified : 32 : 16, 28nm process GDDR5@1000MHZ, 64GB/s 735MHZ
GT 650M DDR3 Kepler (GK107), 384 unified : 32 : 16, 28nm process DDR3@900MHZ, 28.8GB/s 850MHZ


As you can see, talking about dry data, the GTX 660M is actually the same as the GT 650M GDDR5 with higher core clocks. Nvidia’s Turbo mode reported to be working (see some of the games benchmark here) and allows up to 15% increase in speed depending on the sensed temperatures and power consumptions – GT 650M DDR3 GPUs cores were overclocked to 950MHZ. However, this is depends also on the maker of the laptop to decide if she wants to incorporate this feature into the bios. Now, the thing is you can theoretically overclock your GT 650M GDDR5 to the levels of the GT660M core clock. People around the web say you can also OC the GDDR5 from 2000MHZ to 2600MHZ (effective) (1). I wonder, and wished I could check it myself, if the GTX 660M can be OC’ed to the level of the GTX 670M – being an 28nm GPU, its TDP won’t be higher than the GTX 670M while offering the same performance.

What is the difference in practice, you ask? – Well, with the GTX 660M you know that you won’t have issues, probably. It is a designated solution for the stated speed and TDP and you know you’ll get it and supposedly will appear in laptops that can handle the additional 100MHZ and additionally, you get 2GB dedicated GPU memory with the GTX 660M while the GT 650M have also a 1GB version which you usually get (but usually upgradable too). However, it’s only 100MHZ difference which is a joke, so I wouldn’t get to worried if I were to OC the GT 650M. Keep in mind that there is a considerable variation in the cores that get out of Nvidia’s oven. Some cores will be hotter and some less, some will have higher OC capabilities and some less and you should note that with a serious OC’ing, your GPU will probably exceed the stated TDP of 45W for the GT 650M.

Results from notebookcheck. I’ve filtered quirky results. Some of the numbers include the Nvidia Turbo which adds up to 15% to the core clock. Many of the the GT 650M are with 835MHZ (instead 735MHZ), like the GTX 660M, thanks to the Turbo.

Settings GTX 660M, I7-3610QM GT 650M GDDR5, I7-3610QM Difference
Mass Effect 3 1920×1080, all on, onAA 8xAF ~53 ~48 (735MHZ) +10%
Diablo 3 1920×1080, high, on AA ~68 ~60 +13%
Skyrim 1366×768 High Preset 8xAA 8xAF ~50 ~42 (745MHZ) +20%
Dirt Showdown 1366×768 high preset 2xAA, AF ~55 ~50 (745MHZ) +10%
BattleField 3 1366×768 high -AA 16xAF ~40 ~32 +25%
CoD: Modern Warfare 3 1920×1080 Extra, all on, native, 4xAF ~48 ~42 +15%
Max Payne 3 1366×768, Normal, DX10, AF and AA ~55 ~51 +7%
The Secret World 1366×768, High DX11, AF, AA ~36 ~36 (Turbo to 835MHZ) 0-13%

So you see that the theory true also in the numbers.

A word of warning – if you try to OC your card you should watch the temperatures of your system as you don’t want to keep your system on high degree even if it’s working because it unhealthy for the electronic staff.

About the numbers to back up the words. You can take a look in the GT 650M and GTX 660M pages on notebookcheck which include benchmarks in games for both GT 650M GDDR5 and DDR3 models and ofcourse, GT 660M benchmarks. You can see that the overall picture is that the performance difference between the GT 650M GDDR5 and the GTX 660M is very similar to the difference in their core speeds. Remember that the comparison is not perfect as the numbers do not come from the same test machine – different amount of memory in the GT 650M (1GB vs 2GB), different system hardware like chipset and cpu and different – and sometimes outdated – drivers in the test probably had affected the results.


Overclocking the GT 650M

The fellows from NBR forums made some instructions and posted some results of the OC attempts on the GT 650M. The results: the GT 650M GDDR5 is a little hell raiser! Some had success with OC’ing the core up to 1200-1250MHZ (from 835MHZ!) and the memory from 1000MHZ to ~1400MHZ!!

Although each chip is special in his own way, the GT 650M seems to be a very good overclocker. It should not have any problem with going up to the levels of the GTX 660M or close to that.

Concerning heat issues – some people say the overclocking had only a minor impact and besides, you better use a cooling pad to lower the temps anyway, even if you’re not going to OC your gpu.


Conclusions and decision: GT 650M GDDR5 or GTX 660M

My suggestion – I WOULDN’T take a GTX 660M laptop just for being equipped with a GTX 660M GPU. I would look for the overall quality – screen quality, build quality, heat and noise, battery runtime, looks if it matters and weigh it against the price difference. I’ll explain.

As we saw, the GK107 Kepler core in the heart of the GT 650M and GTX 660M should be highly overclockable. The GT 650M can achieve GTX 660M clocks and even higher and it seems pretty easy. It can achieve, therefore, the same performance as the GTX 660M but might exceed the 50W  TDP stated for the 660M. It also raises the thought that the GT 640M GDDR5 might as well be god enough for some decent OCing.

Now, as I figure it, the point with the GTX 660M besides the 100MHZ increase in speed, is that it comes usually with higher end and presumebly better machines overall concerning elements like build quality, heat and noise handling, screen quality, sound and more, but I guess there will be too much exceptions. Anyhow, take, for example, the Asus G55VW and the MSI GE60. The GE60 incorporates good FullHD display, the GT 650M 2GB GDDR5 GPU, 6GB DDR3 and good looks but the G55VW has a more metal body, very good heat and noise handling, also good quality FullHD display and GTX 660M GPU (review), but it costs good 300-400$ more and has no Optimus and low battery runtime. Does it worth it? good question – if you buy a laptop once in few years and you don’t need mobility then it would be good for because you know it has a better chance to survive (less heat, better body). Another example is the Lenovo Y580 can be found with a FullHD display and GTX 660M GPU for 1000$ and the HP dv6t-7000 with FullHD display is on sale for around 900-950$ with coupons in the last month, but still no reviews to tell how much good it really is.

We’ll wait for more reviews of new GT 650M and GTX 660M laptops and write some article about recommended laptops in this league. Meanwhile, I suggest the dv6t-7000 with coupons, the Sager NP6165 – both with GT 650M – to save money. It’s hard to recommend a laptop in this dynamic scene and it’s harder to recommend when there are few good reviews. So wait a bit if you can.


  • Z

    Can you make a comparison among 670m 670mx 675m and 675mx?

    • yea, I’ll do that. I’m working on some stuff now, so I don’t update the site that much
      Anyway, it is something like that:
      675MX ~= 20%-30% 675M
      675M ~= +0-5% 670MX
      670MX ~= +20-25% 670M

      But why these? they are the older 600 series gpus.

      • Z

        XoticPC is selling 16f3 with 675mx around 1000$. It seems like 675mx has similar performance as 770m…

        • yea, I’ve noticed, but it is $1100 ($1070 if you pay cash), it is rather heavy even compared to other heavy gaming laptops like the Y510p and it comes with a 500G 5400RPM HDD.

          So, the bottom line is that it doesn’t have any real advantage over the Lenovo Y510p, that is selling for $1050:

          what do you think?

          • Z

            I really doubt the real performance of the SLI. The heating is a problem for Y-series. SLI seems make this issue more severer

            • 1. The heating is a problem in almost any GTX 770M and even GTX 765M and up laptops currently. Almost all of them throttle, including those that supposedly have a good cooling system

              2. There are benchmarks of the GT 750M on the notebookcheck (and soon here) – the numbers are quite good and sometimes surpass the 770M.

  • for those who are looking for a laptop with gtx660m .. in my case i bought lenovo y580 and it’s cooling is the worst.. it even shutdown automatically in hard gaming use .. because of its cooling is so poor .. the gpu temp reach over 90c measured by speedfan .. so my advise is get a laptop with a high cooling system or whatever.if you want gtx660m search for laptop with a good cooling .. hope its help .

    • some people reported such a problem and some said they can play long hours and the temps are good. When did you bought it and do you know what is the model?

    • Sorry to read about you experience. I bought the samsung np700z7c-s01us 17.3″ for under $800. slightly used but perfect condition. GT650 2GB gddr5, 1080p matte screen, 1tb 5600rpm (replaced with 256GB ssd and bought adapter for 1tb drive in the optical bay, works good but no more optical drive if ever. Excellent battery life, cool temps, very quiet and only 6lbs. Best sound quality so far in a laptop (JBL). 17.3″ but less than 1″ thick and fits perfect in my 15.6″ laptop bag. And gaming of course is excellent. Haven’t tried the overclock yet though. Did clean install Win 7. Highly recommended item.

    • Dean

      Thats interesting, i also have a lenovo y580 with i7 3630qm 2.4GHz and GTX660m and have no problems with heat. in BF3 with high to ultra setting over long periods of time never goes over 65C, i think that is pretty low for a laptop? tested with msi afterburner.

      • Hi!

        can you write the specific model you have? when did you buy it?

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  • Regalian

    Sorry I commented on your other post the GTX 660m GTX 570m and GTX 670m post, since there is quite a performance difference between GTX560m and 570m I’m a bit confused as how this article supports the GT650m = GTX560m and GTX570m < GTX660m < GTX 670m statement.

    • junky

      I probably should have made some article to compare them all and prevent confusion.
      1. The GTX 560M might be averagely *slightly* better than the GT 650M – I didn’t say the 650M equals the GTX 560, but it offers *almost the same or the same performance* – pro. Moreover, In many cases the GT 650M will come with laptops with a faster CPU. In the bottom line, I’ve seen more games in which the GT 650M system is faster for high to highest settings – if you want to know about specific games, just ask.

      2. In the case of GTX 660M vs GTX 570M – as I’ve written in the other article (, the 660M in many cases performs as fast as the GTX570M, especially with the Nvidia Turbo mode.
      It’s something like that:
      GT 650M GDDR5 ~= GTX 560M < GTX 660M <* GTX 570M < GTX 670M * = very slightly. In other words - there isn't really a point in the effort of finding a GTX 570M laptop when you can get a GTX 660M unless there is a specific game you know it's far better (which won't be the case for almost no one). The GTX 660M is also far more energy efficient.

      • Regalian

        Thank you so much for the fast reply! Right now I’m looking at the MSI GE60 which comes in GT650m (2GB DDR5) and GTX660m while all other factors being the same. Hence I think it is safe to say I’ll be able to OC GT650m to the state of 660m according to this article without problems. However, the price difference for these machines is around $150 USD.

        Unless my research from last year is untrue, the GTX570m is much stronger than GTX560m (at least 20~30% stronger is this right?) While searching around the internet these days the GTX660m is only around 10% stronger than GT650m (is this right?) which I suppose is true since there is slightly more than 10% increase in clock rate from 735MHz to 835MHz. And from this article it appears that you’re also saying their performance is not that different agreeing with my research on the internet. But while comparing them to the previous generation it is different to what I expected, hence my question.

        I spent several days on this subject, and I have to say your article is the most in-depth and helpful. Your reply means a lot to me, thank you so much!

        • junky

          The GTX 570M is something like 10-20% faster than the GTX 560M averagly – I guess it’s even more close to 10% than 20% (again, averagly). The 660M is averagly 13% faster than the GT 650M, so it comes close to the GTX 570M anyway.

          thanks for your kind comment (-:

          • Regalian

            Oh I see! Seems like I overestimated the power of GTX570m since I was so keen on buying the MSI GT780 last year. I guess I’ll be going with the GT650m then. Great job on your articles!