I currently use a 1TB mushkin reactor as a games volume. Finally got tired of the limited space on my dual raid0 setup. Still have the first raid as boot, but replaced the games volume a couple or three months ago. tons of space now... more after I make more modifications.... the reactor will, (probably) eventually get consigned to 'general storage'... aka anime, downloads, tax receipts, etc
But before that can happen, I need a new, actual, games drive... been eyeing a samsung 950 pro, or somesuch, but undecided atm. Tbh, after a point, you won't notice the speed as much. Having a system setup with a boot drive and a dedicated game volume, already makes a ton of difference. Even more so if you have enough ram you can ditch the paging file (a different subject)
And, eventually, I'll replace the boot raid. I don't really need a giant drive for that.... but a quick one, that's better at random access and small files. Games, on the other hand, mostly tend to be long periods of nothing, followed by loading tons of texture files, then more long periods of nothing... so a drive that excels at that is theoretically better.
If you're running a single drive system, my recommendation... get yourself a small? fast, ssd, and make it your boot drive. dedicated your existing hard drive to your game volume. You'll gain a ton of responsiveness, both in games, and in general usage. You can add a large ssd later, when/if your game drive dies on you, or you just get tired of having moving parts
(small = 240 GB or so... you'll use about half that on your windows install... get a bigger drive if you want, future usage, less wear, etc)
Remember, like a hard drive, if you fill up an SSD, it slows down a LOT... also, you get more wear on the drive as it starts trying to move stuff around, delete currently unused cells to make room for new writes, etc. Basically, don't fill up your ssd, it's no bueno.
PS: More physical nand literally means more ability to write data to the drive, if you worry about such things. Because the controller literally has more nand to spread the writes across before having to repeat.http://www.thessdreview.com/
(good place to check reviews)