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===Memory===
Obviously, the big question about memory is whether 32bit OS can support memory size of 4G and/or above. My machine is recently upgraded to 4x1G DDR2-800, let's see how many was recognized by various OS'es.

==Testbed==
Motherboard: Gigabyte P35-DS3L  Bios F6 (Support up to 4G memory)
CPU: Intel C2D 6850
Memory: SuperTalent DDR2-800 CL4 1G x4

==Fedora Core7 64bit==
Needless to say, all 4G is usable.

%%
# free -m
			 total       used       free     shared    buffers     cached
Mem:          3968       1008       2960          0         22        450
-/+ buffers/cache:        535       3433
Swap:         1953          0       1953
%%

==Interpreting free==
A side topic to this is how to interpret **free**. Linux uses spare memory to cache I/O operations. Using the above example, 535M is in use by application, 3433M is actually free. This seems to apply to kernel 2.4 only. Ref http://rimuhosting.com/howto/memory.jsp


==Ubuntu 7.10 Desktop 32bit, kernel 2.6.22-14-generic==
Well.. only 3.5G even dmesg says PAE has been enabled & dmidecode sees all 4G of memory modules.

%%
# free -m
			 total       used       free     shared    buffers     cached
Mem:          3546        605       2940          0         86        344
-/+ buffers/cache:        174       3371
Swap:         1953          0       1953
%%

==Knoppix  5.1.1 2007-01-04 32bit, kernel 2.6.19==
Same
%%
# free -m
			 total       used       free     shared    buffers     cached
Mem:          3549        302       3247          0          8        152
-/+ buffers/cache:        141       3408
Swap:            0          0          0
%%

I even passed the mem=4096m parameter to kernel, in vain
%%
# cat /proc/cmdline
ramdisk_size=100000 ...boring... mem=4096m
%%


==Windows XP sp2 32bit==
Boot.ini
%%
[boot loader]
timeout=15
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /fastdetect /NoExecute=OptIn /PAE
C:\CMDCONS\BOOTSECT.DAT="Microsoft Windows Recovery Console" /cmdcons
%%

msinfo32 was able to recognize all 4G of memory
%%
OS Name	Microsoft Windows XP Professional
Version	5.1.2600 Service Pack 2 Build 2600
Hardware Abstraction Layer	Version = "5.1.2600.2180 (xpsp_sp2_rtm.040803-2158)"
Total Physical Memory	4,096.00 MB
Available Physical Memory	2.71 GB
Total Virtual Memory	2.00 GB
Available Virtual Memory	1.96 GB
%%

BUT no surprises there, even with PAE enabled, Windows is only able to use 3.5G of memory. I guess I'm the lucky one already, some see even less than that.
{{image src="images/xp_4g.png"}}