is CM gx ii 650w is enough for gtx 780 lightning

Solution
The minimum PSU is about 600W but I would recommend a 700W for the extra headroom. However it is not recommended to use that PSU for overclocking or having a high end gaming rig like yours. As it is a Tier 4 class, I really advise you to read this before proceeding buying anything.
http://www.tomshardware.com/answers/id-1804779/power-supply-unit-tier-list.html


and try to aim for Tier 1 if you can afford it but a Tier 2 will do too and should be within most gamer's budget.
The minimum PSU is about 600W but I would recommend a 700W for the extra headroom. However it is not recommended to use that PSU for overclocking or having a high end gaming rig like yours. As it is a Tier 4 class, I really advise you to read this before proceeding buying anything.
http://www.tomshardware.com/answers/id-1804779/power-supply-unit-tier-list.html


and try to aim for Tier 1 if you can afford it but a Tier 2 will do too and should be within most gamer's budget.
 
Solution


Why are you referring to a Corsair now. I would actually get it, but please provide the full specs and I will see which PSU suits best and do you have a budget? And keep in mind a good PSU is important or you may loose all your parts when the PSU breaks down or burn.
 


If you don't plan to upgrade in the future, then stay with the 650W. But if you plan to upgrade but you still want to buy the 650W, then you may need to upgrade the PSU. So basically I am planning ahead but who knows what the future holds. :D