Weird RAM Issue (4 X 1024 = 3.5GB)

[kirkbross]

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So I just bought 2048 (2x1G) of Corsair TWIN2X PC6400C4 to add to the two already in there...

Originally I had 2.0 Gb (as displayed in Properties in XP Pro):

Slot 1: 1Gb
Slot 2: 1Gb
Slot 3: Empty
Slot 4: Empty

If I add either one of the new 1024 DIMMS to either slot 3 or 4, it sees 3Gb -- as expected...

But then...

Throw in the fourth and it only sees 3.5 Gbs...

Huh? ...when all four DIMMS are in, it loses 512Mb somehow...

Bios tweak?
_________________________________________
ASUS M2N32-SLI DLX WIFI AM2
AMD|A64 X2 4200+ AM2
ZALMAN|CNPS 9500 AM2 RTL
ANTEC|SONATAII
160G|WD 7K 16M SATA2 WD1600YD
1Gx2|COR 240P TWIN2X2048-6400C4
WIN XP PRO SP2
EVGA EVGA|GF 7900GT 256-P2-N567

[StringCheesian]

32 bit or 64 bit OS?

[kirkbross]

XP Pro 32 bit...

[StringCheesian]

A 32 bit OS does give it's applications a 4 gig address space. However some of that has to be reserved for certain things, so the max is a little less than 4 gig.

You might not be able to use all 4 gig unless you switch to a 64 bit OS.

[kirkbross]

Many thanks.

[joshuapurcell]

Check out this thread if you are interested... it has some information on how 32-bit vs 64-bit distributions see 4GB of memory:
http://www.phoronix.net/forums/showthread.php?t=567

[-|LSV|-]

Check out this thread if you are interested... it has some information on how 32-bit vs 64-bit distributions see 4GB of memory:
http://www.phoronix.net/forums/showthread.php?t=567
Not only!
I use MoBo Asus p4p800 with 4 modules Kingston 1024mb per and have adv problem. BIOS MB exhibit 3,5Gb, when it is established 4 modules.