i was looking into getting a GTX Nvidia 560 Ti because some of my friends told me if i go higher i would get my cpu bottlenecked.(i dont know what that does).
Bottleneck basically means that one part drags the rest of the build's performance down while everything else is fast. Most of the time it's your primary HD. Occasionally it can be the CPU but only if it's a really old model.
Should i get a new parts or a brand new rig. i could sell my old computer to my father and buy new one.
There's things you can certainly reuse - case, PSU, drives, etc, and then you can certainly use a motherboard, CPU, GPU, RAM update and you will still come in well under $1K.
Well the i7 has more cache and hyper-threading, but they tend to perform about the same as the i5 or slightly worse due to hyper-threading's statically allocated resources on Sandy Bridge (fixed in Ivy Bridge). We don't think it's worth the money to pay for hyper-threading for negligible benefit. The 2500K would be a better overclocker but it only really matters if you're looking to go over 4.8 GHz. Also don't forget the Ivy Bridge CPU performs a bit better clock for clock so a 3570K at 4.8 GHz is going to outperform a 2500K at 4.8 GHz (Tom's has some benches in their Ivy Bridge review). The i7 definitely has it's place for heavily threaded applications like video editing, rendering, and hardcore software development.
its only on this site i see ppl recommend I5 instead of I7 , every other gamer vows only on I-7. why is that? and the 3570k is the model for overclocking right?
The main reason most people recommend the i5 is because most games won't benefit from hyperthreading and in some cases it can actually hurt performance. If you're doing other things on the side (video editing, etc) as opposed to strictly gaming then the i7 would be beneficial. In the Sandy / Ivy Bridge world the i5 is essentially the same CPU and it's tailor made for gaming where the i7 is made for other functions besides gaming. Put that money in the GPU instead of the CPU - the right GPU can often make or break a build's performance.