Overclocking question

[DragonTamer1]

I've got a GTX 760 superclocked so I'm not expecting a lot of overclocking headroom (last owner only managed a meager 50MHz core 100MHz RAM), I'm only doing this to gain experience with overclocking and I'm a little curious of how hard I can push the card in benchmarks.

 

My question is how can I tell when my overclock is too high on the core and when it is too high on the VRAM?

[Superiority]

artifacting or crashing will occur, simple.

[DragonTamer1]

This I knew, to clarify I was wondering how you could tell the difference between the two.

 

I'm assuming that if your core is too high then you get crashing, while you get artifacting from the memory.