Talking about bandwidth with low end cards is pointless waste of time. We all know bandwidth matters at high resolutions and high FSAA levels. Meaning none of mid and low end cards can even do it at usable framerates. Only place when discussion about it even makes sense is high and enthusiast level of cards. Those that will actualyl run high res, high settings games at usable framerate. Meaning R9-290X/390X and GTX 980 and above.
Wait, whut?!
Bandwidth matters on every single GPU. Back in the Kepler days there were several versions of the GTX 660 with different memory subsystems. Going lower down the price tiers, you have similar named cards with 64 bit and 128 bit DDR3 and GDDR5 versions. Tell me again bandwidth doesn't matter. Especially on the lower end of the spectrum you can get totally raped if you don't investigate carefully what you buy. In comparison, all high end cards perform far more similarly and are generally very well balanced. The only outlier here is the AMOUNT of memory, where 'bigger is better' is still a very popular marketing strategy.
Talking about lower end hardware may be pointless to you, or us, but especially when you are trying to maximize the benefit of that lower end hardware, memory bandwidth is an essential piece of the puzzle.