What's the max memory i7 processors can use?

I read that i7 CPUs can't access more than 32GB of memory on some forums.

That is an over-generalisation. There is no i7 CPU, there are a lot of CPUs marked as 'i7 something'.

Some of them, like the original core i7 920 can only address up to 24GiB.

Some can address 32GiB. Some might be able to address more.

Just saying 'a i7' is like saying "I heard that some of brand A cars use Diesel. What is the point of having a fuel station which offers petrol for brand A cars ?"