Will gtx 570 will need to be sli"d to get better performance

Yes.More than enough.You can max out crysis with 4XAA and very high and get 40+ fps.Need I say more?

my psu is 700w psu can i sli my gtx 570 with my i5 processor

simply no, it won't be sufficient, besides what is the make of your PSU ? there are 700W PSUs but not capable of handling CF or SLI
get a 850W PSU it will fit your specs and run them fine without a lack of performance

my psu is corsair ..actually i dont want to sli my card ..as there is two pci slots i thought of sli ..so for a single slot p67 board is asrock P67 Pro3 a better one

you say that you don't have an additional PCIe slot ?

i have my boards is msi p67 -gd55..i dont want to sli as im comfortable in running a single card...ok if i add two gtx 560ti will a corsair 650w psu will be enough ah..

You have asked that question several times and it has been answered several times, so stop making new threads asking the same questions.

You need a 700+ Watt power supply unit if you use it in a high-end system (800+ to a KiloWatt is recommended if you plan on any overclocking).

will physx be visually notices when playing games at high res like 1080p

yes if you have a GTX 570 at least or 2 in SLI

which i dont have enough money to buy a gtx 570 so among these cars which is better msi gtx 560ti vs xfx ati 6950

HD 6950

i want physx ..will gtx 560ti will perform best with physx at 720p atleast..i should notice the physx effects visually..to lsi gtx560ti how much watts i need

Did you not bother reading this other thread that you started?

http://www.tomshardware.com/forum/309743-28-corsair-650...

sorry .i dont know how to find my old threads..apologize for my mistake..this will not happen again

so i guess you know what is the best for you now, good luck  

will a single gtx 570 will be really a future proof card

There is no such thing as 'future proof' as something better will always come along.

if my psu is a 750 w i will buy a gtx 570 and i will sli it later if required..my question after 2 years will gtx 570 will be sold coz for sli setup

Maybe, maybe not. Some cards go out of production quicker than others and in two years time you may only be able to get a second hand card from Ebay or similar.

OP:

good lord.... just get a single gtx 570 and see how you like it( I have one and it runs most physx games like batman aa and mirrors edge are the ones that I have they run on high at 1080p with medium-high physX settings) then if its not up to par then sli it, make sure to beg your parents for money at least 2 months in advance for this purchase... thread over