Hi everyone

It's been a while since my last post. I hope you all do fine, and have a great time.

Well, the time has come, I'm about to buy a new gaming PC (Lenovo Thinkcentre, Core 2 Quad Q9400, ATI Radeon HD 7770, 2GB GDDR5)
I'm not much concerned about the graphic card and other spec. since I know it will run smoothly almost any today's game, but I'm just curious about a thing.
Let's say you have 2 (almost) identical graphic cards, including same engine clock, memory clock, both 2GB RAM etc... Everything except the bus/memory interface. The first one (the Radeon HD 7770) has a 128-bit GDDR5 memory interface, whereas the second one (let's say "for example", a nvidia gt or gts model) has a 256-bit GDDR3 or GDDR2 memory interface. I know that the first one would perform better, even though they are theoretically spoken the same except for the bus speed.
Let me get to the point here. What are the difference between a 128-bit GDDR5 and a 256-bit (or 384-bit) GDDR3 (or GDDR2) memory interface? Which one will perform "better"? The 128-bit bus GDDR5 graphic card or the 256-bit GDDR3 one?

Really you are NOT going to notice any difference between these cards as the weak point of this system is the CPU.
The Core 2 is seriously OLD tech and has been superseded by the Core I processor range, which is now in it's THIRD generation.

Really you are NOT going to notice any difference between these cards as the weak point of this system is the CPU.
The Core 2 is seriously OLD tech and has been superseded by the Core i processor range, which is now in it's THIRD generation.

OK, let's say I'll install an Core i5-3570 processor instead of the Q9400. Question remains the same though.

As does the answer..