Originally Posted by unkn(0)wn
Let me tell you , when i play games in windows my ram usage reaches to 3.2 GB in task manager , so windows can't be lying !
How do you know Windows isn't "lying" about that 3.2GB? Or maybe you're misunderstanding the meaning of that 3.2GB stat. Probably, you're also misunderstanding the meaning of the 2.3GB Linux stat you started with.
Of your 4GB physical ram.
1) Part of it is unusable by any OS regardless of what you do.
2) Part of it is usable by a 32 bit PAE Linux or by 64-bit Windows or Linux, and is not usable by 32-bit Windows nor non PAE 32-bit Linux.
3) Part of it is reserved for use by your Intel(R) HD graphics.
3a) Windows (actually NVidia software in Windows) might be able to do things that Linux can't to make part or all of the ram reserved for Intel graphics available for other purposes when the Intel graphics aren't using that ram. That is the only way 32-bit Windows might have more ram usable than Linux on your laptop.
There is a table of physical memory info that the BIOS provides to the OS at startup. You should be able to get it with the command:
dmesg | grep e820
If you post that table to this thread, any expert here can tell you the amount of ram in (2) in my list of possibilities above and the total of (1) and (3) and maybe some estimate of the split between (1) and (3).
That should give you more perspective on the problem and potential for improvement.
For installing the PAE kernel, Ubuntu has a GUI package manager. (I haven't kept track of which GUI package manager is in which version of Ubuntu. Personally, I'm only experienced with the Synaptic
GUI package manager, which is in some versions of Ubuntu).
With Synaptic, it is very easy to search for something like PAE
to find all available packages with PAE in their name. Then it should be obvious which of those packages is the current (for your version of Ubuntu) PAE kernel. Then it is trivial to select it and install it.
Unlike most package installs, a kernel package install does not take effect until the next reboot.