i3 processors are giving a tough competition to even a lot of i5 processors, they are getting powerful, so... Bottlenecking not only happens between the cpu and the GPU but also with what type of storage you have(fast or slow or SSD or HDD) and I don't think the i3 will bottleneck the 1660ti sooo much...some little amount of bottlenecking will be visible but it's pretty normal so no need to worry about that (though I never even have touched a system like that 😩) and oh I didn't realise you asked about the monitor....but I know nothing about anything bottlenecking a monitor, games will work properly though