What is the limit of LowMem and HighMem in PAE enable kernel.
For modern 32-bit PAE Linux kernels - HIGHMEM is 64Gb, LOWMEM varies with amount of memory you have.
The more highmem exists the more memory pressure can be expected in lowmem.
This will result in sudden short-living performance decrease or memory initializing failures.
With SuSE kernels the OOM killer will be invoked before total memory isused up.
For more than 8 GB RAM use a 64 bit kernel!