Performance on the Go
There's really no argument as to whether or not these are powerful systems. They absolutely are, but one of the main desirable features of a laptop is portability. When you compare performance versus mobility between the GX640 and GX740, some interesting points come up.
The first and most obvious comparison would be physical size. The GX740 is noticeably larger than the GX640, and it weighs more too. Yes, it weighs less than a pound more, which may seem negligible, but when you account for its larger size necessitating a larger carrying case, that one pound quickly turns into one and a half or more. If you make long trips on foot often, the additional weight will be something you'll notice.
You also need to consider battery life, and the results in this case really aren't surprising. The GX740's more powerful equipment is also more power hungry, and significantly so. Under continuous use, in general situations (such as web browsing, word processing, and etc), the more power efficient GX640 lasts nearly 2 hours and 45 minutes, while the GX740 hardly manages to survive past 2 hours (these timed tests were conducted with the extended 9-cell battery). With the flush sitting, 6-cell battery, you can expect battery lives to be reduced by up to a third. Needless to say, neither of these systems are battery life champions, but for high-performance laptops, they do post some respectable times.
Now, on top of all of this, you do need to consider performance. This is where things get interesting. Under full load, meaning both the CPU and GPU are running at 100% capacity, both the GX640 and GX740 manage impressive battery lives, 1 hour 45 minutes, and 1 hour 27 minutes respectively. Naturally, if you were to look at this in terms of work units completed, you'd expect the GX740 to take the performance crown, but because the GX640 is so much more energy efficient, it will actually complete about 10% more work units than the GX740: a classic case of tortoise versus hare.
When it comes down to mobile computing, the GX640 is the clear winner, and if you expect to spend the majority of your time away from a plug, you may want to give the GX640 some extra consideration. Although, if that's the case, you may want to consider an entirely different type of laptop altogether.
