If you run the commandcat /proc/cpuinfo
and then look for the line for flags
and if pae is supported it should be shown - similar to this
flags : fpu vme de pse tsc msr pae
mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow extd_apicid pni cx16 lahf_lm cmp_legacy
To use PAE, operating system support is required. Intel versions of Mac OS X support PAE. The Linux kernel supports PAE as a build option and most major distributions provide a PAE kernel either as the default or as an option
(Red Hat Enterprise Linux 6+ kernels expect PAE). FreeBSD and NetBSD also support PAE as a kernel build option.
Microsoft Windows implements PAE if booted with the appropriate option, but current 32-bit desktop editions enforce the physical address space within 4 GB even in PAE mode. According to Geoff Chappell, Microsoft limits 32-bit versions of Windows to 4 GB as a matter of its licensing policy, and Microsoft Technical Fellow Mark Russinovich says that some drivers were found to be unstable when encountering physical addresses above 4 GB. Unofficial kernel patches for Windows Vista and Windows 7 32-bit are available  that break this Microsoft enforced limitation, though the stability is not guaranteed. These tools increase the RAM limit of the 32-bit version of Windows 7 to 64 GB.
For 32-bit application software which needs access to more than 4 GB of RAM, operating systems may provide some special mechanisms in addition to the regular PAE support. On Windows this mechanism is called Address Windowing Extensions.