1. I'm not sure about this one - someone more knowledgeable about graphics cards will have to answer that one.
2. Not entirely sure about that one. I think it more depends on what other hardware you surround your CPU with than the actual CPU itself. The thing about those types of benchmarks is that they never make it clear what other components they test with and they do that so it gives them the results they want. You could theoretically pair an i3-2120 with a Z68 and a 7970 and it will easily outperform anything else in its' path. Coincidentally you could pair a Phenom II X6 with a 990FX triple 580s' and it would yeild similar results.
1) Even though the bandwidth differences are quite a bit different, they are still both low end cards (the ones you listed). So the bandwidth really would not affect much. What would matter more are the timings of the ram - and usually DDR5 has a higher timings (basically the amount of time it needs to communicate) than DDR3.
Even though DDR3 would have tighter timings than DDR5, it still doesn't allow as much bandwidth. This is because DDR3 in simple terms communicates 3 times in 1 pass, whereas the DDR5 would do 5 in 1 pass.
One more thing - it also depends on the bandwidth of the GDDRX's interface. I believe they usually come in 64 bit, all the way up to 256bit. Of course the higher the better in this case. A lot of midrange GPU's come with 128-196bit interface.
So you can see how a lot of video cards could look similar - but can have a massive performance gaps depending on which kind of interface they use for their ram.
I forgot which video card it was....maybe 1-2 generations ago, but there were 2 GPU models, 1 with a 64bit memory interface, and the other with 128bit memory interface. Other than that, they were practically identical, but the 128bit interface GPU performed much much better than the 64bit one.
Just remember I just put everything in simple terms, of course it's much more advanced than that.
for the gpus have a look here: www.hwcompare.com
As for the cpus, the i3 2100 will outperform the amd 955 in games but day-to-day use, i'd pick a 4 core cpu, namely i5 2400.
In other words, if i5 is out of your league, go for the amd.
the only options are : 6750 DDR3 / 5670 DDR5 : i think i will go for 100$ 6750 DDR3 (my screen resolution 1366x768)
However, here at my place a 6770 costs more than 170$, so can't afford that. Moreover, my psu won't be enough for 6770.
in case of CPU:
#1. The benchmarks i referred in my previous post are carried out with GTX 280 at 1920 x 1200. But I just can't depend on them 100%.
#2. I m currently using athlon x2 5200+ at 53 C while i m browsing although its winter time (20 C - ambient temp). So i cant trust amd again.
#3. Eventhough if i go for AMD, i will definetly add a aftermarket 30$ cooler for safety with the new one. This leads me to a situation with just 100$ left for AMD CPU on the same budget. And i don't think any x4 athlon or x2 phenom will outperform i3 2100 in gaming.
#4. i3 2100 is far more energy efficient.
#5. It will open a way for future 22nm IVY BRIDGE.
#6. Lastly, I and the leading-shopkeeper at my location had a lot of issues replacing the previous athlon'mobo to eradicate the overheating issues and is so kinda angry about the new AMD purchase. Again, it doesn't matter a lot bt if i want to have better cooperation with him in future, i think i must accept his advice and opt for intel.
<Plz dont suggest me to mount a 30$ cooler on my current athlon and invest the rest on GPU. i just wanna get rid of this AMD thing i m stucked into>
?1. a DDR3/DDR5 difference doesn't matter much at such low resolution, i.e., a 6750 DDR3 will marginly outperform 5670 DDR5.
?2. i3 2100 is better than any AMD cpu in playing CRYSIS as mentioned here
You seem to already believe the i3 is better than any AMD solution in that situation according to those benchmarks, so I guess the whole point here is to get reassurance. According to those benchmarks, it's better than anything other than the 2500k and 2600k, including a non K i5 and multiple first gen i7s.
BTW, GDDR3 is not 3x and GDDR5 is not 5x. GDDR3 is 2x and GDDR5 is 4x. It would make a difference when you can saturate the bandwidth enough to need double the bandwidth. Then again, if you don't need double the bandwidth, why would you need a better GPU?
We are basically talking very similar prices between cards in range of 6750 to 6790. Check it up on newegg. The difference between them is a good chunk of fps, for the same price and it IS a whole different gaming experience.
If you like the i3 then go for it, but not investing like 10$ more on a far superior gfx card is silly, no matter how tight your budget is.