View Full Version : [ubuntu] 10.04 installed PAE - why?

May 24th, 2011, 02:47 AM
I just installed 10.04 on my daughters computer, it is an older Athlon XP 2400+ motherboard. Ubuntu installed 2 kernels, listed in Grub (it is also dual boot w/XP).

Kernel 2.6.32-31 pae


Kernel 2.6.32-28

I looked it up and "pae" is installed on computers with over 3 GB of memory, this comp only has 768 MB. I would guess that maybe it didn't recognize the memory properly, being as it is an old motherboard (10+ years).

Which kernel should I use? Is a problem to just leave it as is?


May 24th, 2011, 03:13 AM
After the first set of updates, I now also have "Kernel 2.6.32-31" without pae, so 3 total. I would guess that would be the best one to use. Am I right?


May 24th, 2011, 05:26 AM
PAE is physical address extension. It allows a 32-bit kernel to address 4 GB or more RAM. 64-bit kernels (amd64) have a large enough address space to address several GB of RAM. I don't know what the theoretical limit is, but it's much, much larger than current motherboards support.

Without -pae, you can only address ~3.2 GB when you have 4 GB installed on your machine. If you have less than 4 GB, then don't worry about it.

May 26th, 2011, 04:49 AM
Just an added note to this thread.


Old motherboard ~ 10 yrs old give or take a couple.
No BIOS updates available, (that would fix 'problem' )
4 Gig of Ram
PAE kernels and non PAE Kernels.

Perceived problem :

Can't address > 3.1 of Ram with PAE Kernel

Attempts at Resolution:

Postings made, numerous postings on what to do, various solutions were provided (Thanks all) but no resolution.

Finally !!!!!! (Obvious now I'm informed) The MOTHERBOARD!!!!! needs to be able to provide support for PAE addressing in BIOS.

Thunderbolt of insight strikes Ahh, but I can't get UPGRADED BIOS support.


Old motherboard= Non PAE SUPPORT.
>4 Gig of Ram (which I have) is going to waste.
Motherboard will only support 2 Extra Dimms, of 4, so Extra is either its 2x 512Meg Dimms for 3 Gig of Memory, or 2x 1Gig Dimms (I Have) for 4 Gig in total.

So I'm left with some memory not being addressed. Though I never even come close to using 1/2 of it when running games. So Meh!!!! Gave me something to solve to 2 weeks.