Can I upgrade to Zotac Gtx660ti.
 

My system spec:

cpu:phenom x6 1100t BE 3.3ghz.
mb:jetway hummer HA12-LF.
psu:coolermaster extreme power plus 650 watts(RS-650-PCAR-E3).
ram:GSkill ripjaws x 1333 mhz 8gb (4gbx2).
cpu cooler:hyper 212 evo.

and a question that what will be the difference between zotac,msi,galaxy 660ti.

reference cards? nothing really cept warranties and CS

it means i can upgrade to 660ti with out any bottleneck &is my psu good enough to handel it 24x7.
by the way what is CS?

I dont know about that one in particular but a 650 should be more than enough and I meant Customer service (sorry lol)

Your PSU should be sufficient for the 660ti.
Many of the cards currently available have slightly different clock speeds, as well as different bundles and aftermarket coolers as well. With your processor you shouldn't have to worry about your GPU being bottlenecked, and if you want to run it 24/7 make sure the case wiring is tidy, and your airflow is unobstucted.

Thanks Guys...

If your worried about bottle-necking from the cpu, overclock it.. thoes are quite good clocking chip... find a how-to somewhere..

may be i am thinking about sapphire 7950 3gb ddr5 because both prices quite same in india .
zotac amp edition 2gb ddr5 660ti vs sapphire 7950 3gb ddr5 which one is better according to you all guys.

Prices will be fairly close together.. at single screen at up to 1920x1200 resolution you'll see no real difference (depending on game, some prefer different chips)

If your going larger resolution then the AMD is better but that one won't really be able to handle a 2560x1440 screen or multi-monitor set-up on it's own
and the support for sli is much better than x-fire anyway..
Really it's personal choice but I would be happy with either for a single card and more likely to go nvidia as they are more stable with their driver releases..

As I said.. personal preference. (P.S the ram doesn't come into play till you hit really big resolutions..)

Not the best power supply in the world, but you should be good to go for the 660ti. You won't be bottlenecked by anything else in your system.