I just got my rig yesterday and will be overclocking my CPU to 4.5ghz.  I was wondering if I should also oc my video card.  Here are my specs:
INTEL I5-2500K 3.30 GHZ            
120 GB OCZ VERTEX 3 SATA III SSD                        
RIPJAWS X 8GB 1600 MEMORY WITH HEAT SPREADER
THERMALTAKE FRIO OVERCLOCKING COOLER               
BLACK AZZA HURRICANE 2000                                                     
GIGABYTE Z68X-UD3H-B3 
CORSAIR CMPSU-850TX V2 POWER SUPPLY 
ZOTAC GEFORCE GTX 570 1.2GB DDR5 PCI-E 
I have never overclocked a video card and do not know if this is one that should even be overclocked.  Any advice or suggestions are appreciated.
Thanks,
Derol