Memory interface

Yes it is good.but you need to specfy gpu which you want to buy.'Bit doesnot matter benchmarks matter'

Agree.
Don't get hung up on the little details when the broad strokes of gaming benchmarks are easy to find.

I believe the lower-end GTX600 series had a slightly constrained memory bus, the primary result which was to cause a notable performance drop above 4xMSAA. On the other hand, most people wouldn't game at over 4xMSAA on lower-end cards.

Long story short is:
a) pick a BUDGET for a graphics card upgrade
b) Google reviews for cards in that budget and compare

I'd probably be recommending the AMD HD7000 series below $200 (HD7770, HD7850, HD7870) depending on your budget.

Oky thank you, but is the ASUS gtx650 TOP a good choice to consider ?

Please tell your pc specs,max resolution and budget.