Im wanting to OC my GFX card...

[Kittra]

Honestly, I can't really see overclocking your GPU helping out much. Usually overclocking by 100mhz results in a 2-4 fps difference and you'll eventually hit a "hard cap" if you don't also overclock the CPU.

If you still really want to do it though to see if it will improve your game at all, I recommend downloading either MSI Afterburner or ASUS's own GPU Tweak.
Both programs should make overclocking your GPU easy and they're each free to use.

I recommend increasing your Boost Clock (ASUS) or Core Clock (MSI Afterburner) by 20-30 mhz and play the game a little until you start noticing problems and then dial that back a bit till the problems go away.

Seeing as you have a 650 Ti BOOST, it's already factory overclocked so there's not to much more you can overclock it by till it hits it's upper limit.

*EDIT*

I also figured I'd mention that since you have a 600 series card, they're less "Overclock friendly" meaning they have some safety features in their bios that will kick in if certain limits are crossed, making your overclock completely pointless in the long run.

Are you having problems running the game or are you just trying to get the best performance possible out of your system? (I can understand that)

[Gamemako]

Do tests with FurMark for checking for errors after overclocking. Go up in small increments, check stability as you go with 5-minute tests. Once you get a crash, see artifacts, or get FurMark errors, back off to the last stable test point. From there, drop back by 30-50mhz, and run FurMark overnight to test stability. If it's not stable, back off some more. Remember that you want to be sure it's stable. Also, watch temps -- GPUs are designed to run hot as hell, but you don't want it to breach 90 (100C is the usual design window, and you should always leave some wiggle room for hot days and degradation). Crap fans will give you limited room for overclocking, obviously.

[Celestris]

Do tests with FurMark for checking for errors after overclocking...

I used to do the same thing, until I read from other users that Furmark is really only good for cranking up your card's temperatures as it doesn't really test real scenario usage of the card in terms of what type of processing and such is done. They have suggested using Unigine Valley instead (http://unigine.com/products/valley/). Running through this a couple of times should help you be more confident in your card's stability. They have a benchmarking feature as well so you can see if there are any improvements when you increment your overclock.

That being said, the only real way you're going to know if your card is stable is to play the actual game for a while. If you don't crash (say after a week of playing) congrats, you're probably stable for FFXIV! Because FFXIV (and all other games) use graphics card for processing in a different way, the card still might crash when playing other games though. Good luck OP!