Let me explain. Right now I mainly need a new GPU because my new one is horrible (1GB VRAM is horrible for nowadays games) since many games require 2GB just for the minimum requirements. I had 2 options: Either buy a real good GPU but then also get a new CPU (or else there's no point) and for that a new MB and a new RAM etc.... or just get GTX 1650 which is good enough for me.
I saw in some place that this GTX may bottleneck old CPU. The question is how much. Based on pc-builds calculator it's around 10% which is fine by me, but someone told me this calculator is not accurate. Knowing how much it will bottleneck (or in other words - will not be effective to my PC) is super important because if let's say it's 50%, then what's the point? I'd better get a new PC and I don't want to unless I really have to.
Where I'm from even GTX 1650 is expensive ($420) so I have to know I'm making the right decision
Bottleneck calculators are utter crap.
You can't say that your system will be bottlenecked by 10% in everything because not every game uses the same resources or has the same requirements.
For example if you play CS:GO that is very heavily CPU bound, the older CPU will hold back the performance by a huge margin when compared to new gen CPUs. When you play Tomb Raider, the GPU becomes also very important so better GPU will help more.
In the end it matters what games you play, at what resolution and what settings because each and every game handles the resources differently. So the "bottleneck' (which I hate that term) can be calculated for a SPECIFIC game, with SPECIFIC resolution and SPECIFIC settings on your SPECIFIC hardware.
Also, you said:
or just get GTX 1650 which is good enough for me.
That should have been the answer here.