you can also put it like this: most steam machine start out with a 750ti, next step up is like a 960.
now if steam condons those mashines (which they do proudly) to perform as good or better than any console (ps4,xbox one) then a 750TI is plenty ATM.
since you already have it there is no reason to up grade,
if you are having performace problems then it might not be so much your 750TI, as it is still relavent and sold very populerly for gaming.
but instead might be another one of you components that is actually bottle necking the 750TI.
because; as , TNT27, mentented his functions perfectly with BF4, and if that works most games therefore must also be playable on your system as well,
only reasone i can see them not working is if you are trying to play 4k or have a 144hz monitore with 1440xsomething or you genuinely need more speed for a any given game,
which in that case i would reach for a higher card as a 760 will put you in the exact same boot you are in now, addtionally it will wast your money for potnenial other reasons or upgrades both cards in that case could be running too slow.
I dont think i ever saw any spec. of your rig. but we would all be more than happy to take a look for you than argue about a 750ti vs 760 which really has no point to unless this guy on craigslist is selling it to you for like 25$, I can almost guarantee you he is going to sell you that card, turn around and buy a better one, with the 150$ or dollars that is burning a hole in your pocket, or it is a lemon, as craigslist, bluntly put has turned into a really shady place from where it once originated from.
so either way i don't recommend this AT ALL. if you look in the forums here a bit and have some patience you might even find better deals, two weeks ago there was a 660TI for 100$ MSI now that might have been worth it as you could have easily overclocked to a 770 nievo level and it would be safer and though pay pal. same goes for ebay check there at the "buy it now" sections. a lot of time also bargains, if it doesn't work ebay & paypal have your back. while craigslist will do the opposite and distance themselves, not wanting to get sued for rape.
And when you buy a new card ^^ shoot for the stars not for the next best thing that comes around, it goes for life too. have a good night y'all.