The 2nd generation was very capable not much has changed since then there is a 25% improvement in single threaded from 1st gen to 4th gen so you can obtain that 25% by a nice overclock, i have seen people run their 2nd gen i7 with Cards like the 980ti in 2x sli. Idk why people argue that the older generations were so poor. Getting an i7 would not cost you much as it would be used and i have been using refurbished stuff for like 10 years and it all depends on what kind of person you are buying it from, if you are saving tons of cash by using the older generations that's great and you can spend that money on the graphics card.
All i have seen is that improvements are due to the internal gpu that is the only thing other than die shrink that intel focuses on.
Only get it if:
- you are saving tons,
- can oc it nicely and keep it cooled
- getting it from a trustworthy /reliable person
This is coming from someone who has been thoroughly used almost all generations of intel i series processors (except skylake and will be getting to it soon.)