14.04 on 32bit T2300 with PAE only seeing 2.9GiB of 4GiB

[stm146]

My old Acer Aspire 5610 was too slow switching between windows so I've just upgraded from 2GiB to 4GiB ram. However, according to system monitor I only have 2.9GiB. 4GiB is shown in bios and sifting through the info generated by sudo lshw I see 4GiB system memory. I also notice that the bios capabilities listed by lshw don't include PAE, but the cpu capabilities do include PAE. I'm wondering if PAE wasn't set in bios when I installed 14.04 as at that time I only had 2GiB ram. Grateful for any advice on what's wrong & how I can fix it.

[slickymaster]

Are you using an integrated video card without dedicated memory? That will take up some of your RAM space to operate.

[sudodus]

I'm not sure, but there might be limitations in the motherboard as well as in the CPU concerning PAE. But I am almost sure that a computer model that is delivered with an Intel dual core CPU has a motherboard that can manage an operating system with PAE and manage 4 GB RAM.

What operating system are you running: Distro, version, architecture, for example Lubuntu 14.04.3 LTS 32-bit (which has a PAE kernel)?

There are some alternatives with non-PAE kernels, for example community re-spins of Ubuntu 12.04 LTS, that have the problem you indicate with more than 2 GB RAM.

I suspect that you are running a non-pae operating system. You might be able to upgrade to a PAE kernel (or re-install a PAE system), and take advantage of all the RAM.

But before upgrading or reinstalling, I suggest that you try Lubuntu, Xubuntu, or Ubuntu MATE before installing it. Try a system with PAE, for example Lubuntu 14.04.3 LTS 32-bit, and check if all the RAM can be used

[stm146]

@slickymaster - The Intel GMA 950 has a max allocated memory size of just 244MiB so I don't think that explains the missing ram. I suspect it may be something to do with PAE not being enabled in bios, but I don't know enough to be sure.

[stm146]

@sudodus I'm running Ubuntu 14.04 LTS (32 bit). The laptop spec says it can support 4GiB ram.

[Yellow Pasque]

I'm not sure, but there might be limitations in the motherboard as well as in the CPU concerning PAE.

From what I've seen, the 945 chipset won't support PAE. It doesn't support 36-bit addressing like the 965 chipset. You'll see other folks complaining of the same thing. https://forums.opensuse.org/showthre...mory-disapeard

Anyway, if the system is slow to change between windows when running Unity, I would suspect graphics performance. 2GB of RAM should not be limiting basic desktop usage. Try a lighter desktop environment (like xfce or MATE).

The laptop spec says it can support 4GiB ra

It will boot with 4GB of RAM, but it won't make all of it addressable. Of course, the specs don't mention that part...

[sudodus]

I'm not sure, but there might be limitations in the motherboard as well as in the CPU concerning PAE.

From what I've seen, the 945 chipset won't support PAE. It doesn't support 36-bit addressing like the 965 chipset. You'll see other folks complaining of the same thing. https://forums.opensuse.org/showthre...mory-disapeard

Anyway, if the system is slow to change between windows when running Unity, I would suspect graphics performance. 2GB of RAM should not be limiting basic desktop usage. Try a lighter desktop environment (like xfce or MATE).

The laptop spec says it can support 4GiB ra

It will boot with 4GB of RAM, but it won't make all of it addressable. Of course, the specs don't mention that part...

Thanks for this explanation

So you'll have to get along using only part of the RAM. But I agree with Temüjin, a lighter desktop environment should make the computer work well anyway, Lubuntu with the ultra-light LXDE or Xubuntu and Ubuntu MATE with the medium light XFCE and MATE should all work well. Try them and select what you like the best.

[stm146]

@ Temüjin - thanks but I can't see anything about the 945 chipset not supporting 36 bit addressing at the link you posted - https://forums.opensuse.org/showthre...mory-disapeard -
.

[Yellow Pasque]

945GM - Physical Address Extensions = 32-bit
http://ark.intel.com/products/27857/...ory-Controller

GM965 (successor to 945GM) - Physical Address Extensions = 36-bit
http://ark.intel.com/products/29821/...ory-Controller

[stm146]

945GM - Physical Address Extensions = 32-bit
http://ark.intel.com/products/27857/...ory-Controller

GM965 (successor to 945GM) - Physical Address Extensions = 36-bit
http://ark.intel.com/products/29821/...ory-Controller

Thanks for these links Temüjin. The first link confirms that the 945 chipset supports up to 4GiB so still I don't understand why Ubuntu only sees 2.9GiB.