NAMAZEE :
thanks for your reply but the oc version is not within my budget.....bydway how much performance difference is there between the oc and normal versins?
for your native resolution i.e. 1366*768, there won't be any significant difference. you can easily go with non-oc version. but it is evident from other posts that flipkart is giving huge discount on Gainward 650 ti card. if it is within your budget then go for it, its better than hd 7770.
One thing to remind you though that Sapphire is a much better company than Gainward. So sapphire cards are more reliable, runs cooler and better overclockable if required. Ultimately its your call.
you can check this link out to see the graphics card hierarchy:
http://www.tomshardware.com/reviews/gaming-graphics-card-review,3107-7.html