The difference is that FF14 is poorly coded. The short of the long is that overclocking causes data to be lost. Normally, this just means that the processor has to re-calculate X number instructions, but you end up with an overall performance increase because the added speed makes up for the lost data and recalculations. FF14 however, being poorly coded/optimized does not handle that lost data well at all, and can crash. Not all people experience this problem - it depends on your card, how much its overclocked, how the chip is flawed (every chip is flawed; thats why some are rated at X speed and some Y speed even though they came off the same line). I would suggest turning off all your overclocking and least test to see if you have the issues with FF14 while its off. If it works, you know the cause. If it doesn't, you should be fine obviously.