Need psu for 3570k

[blazetro]

guys please suggest me a psu for overclocking i5 3570k upto 4.2ghz.......(at lowest cost as you can)
my other specs
ati 6670 1gb ddr5 gpu
2x4gb corsair vengence ram
asrock extreme4 mobo

 

[jay_nar2012]

http://www.amazon.co.uk/Seasonic-S12II-520-520-Power-Supply/dp/B003M2YQYO/ref=sr_1_35?ie=UTF8&qid=1355765006&sr=8-35

 

[alvine]

550watts to be safe