Liquid cooling solution seems very enticing but I was wondering how frequent do leakage occur on them. Do Corsair ones use non-conductive liquid? And is Liquid cooling unnecessary for non-overclock systems?
I take it you're talking about the AIO coolers like the H70 ETC...
They're generally very safe, it's rare for one to leak. I don't know of any liquid that is non-conductive for any length of time once it's in contact with metal so if the coolant leaks onto your motherboard for example you'd need to go through the process of removing the motherboard, cleaning it properly and the letting it dry for awhile.
If you are not overclocking then the stock cooler is generally good enough