GTX 660 TI or HD 7950 ?

HD 7950 for sure.

what is the effect of
Lacking phyics will cause
1)slow games
or 2) no phyics at all like wind ,particles ,dust,etc......
??????????????

PhysX uses the Nvidia card's GPU to calculate advanced physics like glass/concrete fragmentations, but it can basically do any physics related tasks from cloth and fluid simulations to special effects such as dynamic smoke, sparks and explosions. If you try to run PhysX without an Nvidia card it will force the load on your CPU instead and cause massive lag.

The thing with PhysX is that very few games support it at all and in several cases the effects can be so subtle that most people would not even notice them. It's most apparent in games like Borderlands 2 and Mirror's Edge, which utilize it to its full extent. The list of PhysX compatible games is quite short and some AMD fans like to even refer to PhysX as; (Quote: ) "Some pebbles getting kicked around."

Here's a list for all games using Nvidia's PhysX http://en.wikipedia.org/wiki/List_of_games_with_hardwar...

Well according to benchmarks the HD 7950 will perform better than the 660ti

source:

http://www.anandtech.com/bench/Product/550?vs=647

First of all CPU can handle Physics just fine, most game engines are designed around CPU physics alogorithms. Physx enabled titles benefit from Nvidia of course, though the actual game support is poor. BattleField 3 has some of the best physics but is not a Physx title! Borderlands 2 is only one title the rest are a few years old now, only 40 titles since 2007!!

The 7950 can be the fastest card on the market with a medicore overclock, it also has the bandwidth and vram to match. The 660ti is too cut down, less SMX unit and less bandwidth amongst other things.

Best answer selected by TRex2142.

thanks for all of you guys
i will buy hd 7950.
screw the physics, i will never forget the option in NVIDIA Control Panel ''physics rendered by cpu,gpu or automatic''
i only have borderlands 2 ,metro 2033 &mirrors edge that have so much physics

i don't think my core i7 can't handle the physics

never forget that physics system was born 6 years ago
and only 5 important games used it partially
again thank you