PCIe is backwards compatible, so don't focus much on the 2.0 aspect. Newer GPU's will run just fine.
What PSU is in there? That'll play a factor too.
With an i3-2100, I personally wouldn't pair anything greater than a 1050ti or RX460 (maybe an RX470) - but those are ~75W (1050ti's) to 120W (RX470), with some variants of 1050ti's and RX460's needing Aux PSU power, and all 470's needing it..... your PSU will be a big factor.
I have a i3-2120 from 2011 and I recommend getting a 1050ti or 1050 or maybe even a Rx 460. The reason i suggest these is because i have a 1050ti in my build and i haven't seen any big bottlenecks but maybe just a little, But you will be fine.
I'm from Mumbai, India.
I'm convinced with gtx 1050 ti and definitely going for it. Just psu is the issue cause i have limited budget. What if i go for Corsair CX 430 ( 3500 rs or 52 USD). I can't afford beyond that ( i am a student and totally dependent on my father for money
EVGA psu's that you mentioned are not available here in India (atleast in online markets; not sure about local stores)
After some research I found these popular psu's which got good reviews online and they are in my budget. These are the best psu's that i can afford.
Antec VP 450P
Antec VP 500PC
Cooler Master B500
Cooler Master Thunder 450W/500W
Corsair CX 430M
Which one should I choose now?
Seasonic s12II 520W is also there but it is just going beyond.
I will only say , according to thom's own PSu teir listing ,my Corsair CX is like the worst I could have for my computer, yet, its have been working without a single glitch for 6 years now.. so looking at that listing as a reference I would have to be forced to say seasonic, only because India power lines are not the best filtered power lines in the world and you better have a proper "really strong" PSU dealing with the "shenanigans the currents will bring "
@SuperSaiyan10, If you can stretch to the S12II 520W from SeaSonic, that would be a very smart move long-term.
If not, the Antec VP450P is the best of a relatively poor bunch.
@The Paladin, the older CX lineup is by no means the worst you could have. I've seen plenty of poorer options while browsing to assist members in India (lots of off-brand, Diablotech etc), but it's also very, very far from the best. You also have the CX750 (from you sig), which is actually a little better than the lower-wattage 430/500's. The new CX's are acytually pretty good (CX450M / 550M / 650M)