I'm guessing the Multiplayer Online Battle Arena games you play are similar to League of Legends, DOTA 2 or Heroes of Newerth - these types of games don't need a lot of graphics power to run well at 1080p, but if you wanna run games like Far Cry 2/3/4, Crysis 1/2/3, Assassin's Creed 3/4/5 or Rogue and Battlefield 3 or 4 at high settings, you're going to need a more powerful graphics card like an R9 285 and even a more better CPU like an Intel Core i5 4690k.
I would get the fastest CPU for your motherboard unless u gonna update that too. Which is a 3770k atm. My next thing would be upgrading that 650ti to a 770. You can find them near 200 on ebay used. Most MOBA benefit from higher clock speeds. I would get a decent cooler like Cooler Master Hyper 212 Evo or plus or AIO unit and OC that CPU to at least 3.7Ghz
you don't NEED a 4690k, nor a 4670k, nor a 3570k. i would try to obtain a 3570, which will work with your board. your card should be able to handle all the main MOBA games at high or max, near or at 60fps. But, you could always get a new one if your FPS game choices are more taxing. i would also consider getting a simple 120Gb SSD. make things snappier.
What sort of budget are we looking at for this upgrade?
this should give you an idea of how the GTX 970 performs vs the R9 290: http://www.youtube.com/watch?v=_wEOK6Hf4h8
keep in mind that comparison was for 1440p... you'll have to keep VSYNC on to keep the screen from tearing with any of the above listed for a 1080p 60hz monitor...
it's definitely worth the extra $25 over the Asus 290 (though that is a really nice version of the card)... I can't see $40 holding me back from it for the MSI version... I could maybe see saving $70 for the Gigabyte model making me double-check...
then again... if I was going to get the Gigabyte model I'd definitely chuck out the extra $30 for the MSI... and if I was gonna do that I wouldn't flinch at the extra $15 for the Asus model lol.... which brings us back to the 970 which is the superior card :P
but regardless... all those cards will murder 1080p... i3 bottleneck or no...