The 980 is a newer, stronger GPU that leverages the new Maxwell GPU architecture from NVIDIA. The 780 uses the older Kepler architecture, although both are strong GPUs for gaming.This chart shows a comparison using 3D Mark Vantage:As you can see, the difference between the two (for this benchmark) isn't huge. Since the 980 is using the Maxwell architecture, it consumes slightly less power (165W vs 250W), which could be valuable information if you're building a system. See the following pages for more details:GeForce GTX 780 | Specifications | GeForceGeForce GTX 980 Graphics Card
I think everything of relevance has been mentioned... The 760 packs more power than the 750. 4GB is nice, but it's pointless if you the card doesn't have the power to support it, and the 750 just doesn't. The 4GB was more or less to confuse ill-knowledged consumers in the hopes of increasing sales, though the 4GB of VRAM was probably done to help the consumer over-look the lack of SLI. SLI was a big thing briefly, until we noticed that you get more usable power from a single higher tier GPU than two lower tier GPUs. Really the only reason to get a 750 would be if you wanted to go against the grain and were on a tight budget and wanted to buy something with pointless higher box numbers than other things on the shelf. That is to say, you walked into the store and said "oooh 4GB is more than 2GB, so it has to be better no matter what anyone else said".
A very Important Question about Lenovo Y50 GTX860M Maxwell or Kepler?
google GPU Z and download it. Good tool for GPU indentification. And 860m kepler is 4gb and maxwell is 2gb according to this link: http://www.notebookcheck.net/Review-Nvidia-GeForce-GTX-860M-Maxwell-vs-Kepler.114908.0.html also check out the performance of both cards in the link.
Which laptop has the better specs out of these 2?
Definitely Lenovo. It has more ram and a hybrid disk (both SSD 8GB and HDD, the rest). 8GB SSD is really not much, so I'm not sure it makes that much of a difference. If you know the OS alone is around 15GB these days... It also has better speakers. Otherwise, the specs are pretty similar besides the size of the screen. The question is, do you really want a 15" or a 17" screen? You can later always upgrade to more ram (you're most likely not going to use more than 12GB) and you can always upgrade your disk as well. The screen is one of the things you cannot upgrade on a laptop. I would most likely go for the 17" screen and upgrade later on when the money comes in.
GeForce 830M 2GB is a Middle-Class Mobile Graphics Card based on the First Revision of the Maxwell architecture.GeForce GT 650M is a Fast-Middle-Class Mobile Graphics Card based on the first revision of the Kepler Architecture. Check this link below to know moreNvidia GeForce 830M 2GB compare Nvidia GeForce GT 650M GPU
Go for the 940M, its cheaper and somewhat faster than the 840M.Next time you could use this: GPUBoss for comparing video-cards. If you want a more in depth approach try Pick Parts, Build Your PC, Compare and Share But you'll need to get down and gritty with spec numbers and such.Go to the YouTube channel: Techquickie , it does a pretty neat work at explaining things or sort of easing in some arcane pcgaming and building concepts for newcomers.
NVIDIA GeForce 840M is based on Nvidia's new Maxwell architecture (GM108 chip).The 840M offers 384 shader units as well as DDR3 memory but a "64 bit" memory interface.Owing to 64bit memory bus width, it will be limited during memory intensive processing(like at high resolution, using high Anti-Aliasing effects etc) but due to architectural improvement (of "Maxwell") this flaw is diminished besides most laptops have 1366x768 resolution which can be handled easily compared to other higher resolution.While the NVIDIA GeForce 740M is based on Nvidia's older Kepler architecture. It also offers 384 shader unit but offers 128bit memory interface thus negating the memory bottleneck caused due to bus width.Moreover the memory bottleneck here will be more evident because both graphics card uses DDR3 memory interface rather than GDDR5,and according to benchmarks, the GeForce 840M is about 30 percent faster than the old GT740M and just slightly behind a GT750M (DDR3 version). "Many games of 2013/2014 can be played fluently in WXGA resolution (1366 x 768) and medium or high detail settings. However, very demanding games such as Crysis 3 or Battlefield 4 will require lower resolutions and/or details."The GT840M seems superior to GT740M mainly due to superior architecture, you can go for GT840M.
920M is with a Kepler Architecture and 840M uses a Maxwell Architecture, although, 920M is 2015 model and it is basic version, where as 840M is a Middle level. GeForce 840M is good, and recommended a 4GB ram. These models are outdated, you can buy these graphics cards for an economic price.If you want a comparison of these, check it. Nvidia GeForce 920M 2GB compare Nvidia GeForce 840M 2GB GPU