Less RAM is shown than there actually is

Hi, I just downloaded this program and I can't figure it out. Why can I only use less than 2gb if I have 4gb? (my video card has a dedicated card of 2 gb, if that's the case, how do I make the program use the other one?)

Perhaps you are using a 32-bit OS?

No no, it's a 64-bit.

I managed to use 2,5gb now but instead of gaining performance, my ram went to 90% usage.

Perhaps you don't quite understand what a RAM disk is. It's not a magical solution to boost computer's performance or increase its RAM. It allows you to have a super-fast disk in unused RAM, so generally slow disk operations e.g. on temporary files could be done in RAM and completed faster.

In your case, although you have 4 GB, it's likely that 2 GB is used by the OS and apps with only 2 GB left. So naturally only that unused space can be allocated to a RAM Disk. If you do so and allocate most free space to a RAM Disk, your system will have almost no free RAM left, which will instead slow everything down.

Perhaps this article can shed more light on what a RAM Disk is and how it can be used.

Basically if i store almost 2gb on the ram disk with 2gb, the program that i run in that partition will not work properly in any case because the system is at its ram limit, is that it?

That's right. You should only use a RAM Disk where there is unused (excessive) RAM.