Can i choose a limited use of my memory ram by Haiku?

I don't think there's yet a way to tell Haiku to use less memory at boot.

You might put that in as an enhancement ticket though here: http://dev.haiku-os.org

I would possibly even request something more advanced - like the ability to configure a blacklist of memory areas. I know some machines come with soldered RAM and an optional expansion slot for more RAM - sometimes the soldered RAM goes bad, leaving the user with few options.

On the other hand, this is a pretty specialized request that will probably be extremely low priority.