Is my psu an over kill

With a simple calculator like this one
http://images10.newegg.com/BizIntell/tool/psucalc/index...

I got about 400 watts. Note that you have an overclocked GPU and if your CPU is overclocked, the PSU is in no way overkill. I do not see how the PSU could kill the GPU like that. If the PSU is new it may be a bad PSU. OCZ is not a top brand.

The guy at the shop is full of crap. The job of the power supply is to provide the proper ammount of current to each component. It doesnt matter how powerful it is, it is supposed to regulate power output. You could get away with a less powerful psu(around 500watts), but 600 watts is by no means overkill. You could run a 1200watt psu in that system without harming anything, if the psu works like it should, but that would of course be a waste of money

No. You need find a better computer shop.

No not at all.

The shopkeeper sounds a really funny because he is advising something which could never happen, damage any component even though the system power is overkill which is not actually overkill.

The psu will provide only the power required by the cpu and the extra power gets holds or is rejected by the psu until or unless system requires extra power.

May be your PSU be at a fault.Try getting some standard psu from either Seasonic or Corsair.

Thanks to every body for getting back so quickly.I thought he was talking crap, i just wanted to verify thanks again.