4GB of RAM not recognised on x64 xp

philjayj · 8 Dec 2007 at 17:53

Hi

I have just installed 4GB of RAM on a newly-built Windows XP Pro x64 edition. When in windows, only 3.37GB of RAM is recognised.

How can I 'unlock' the rest?

Cheers

Phil

rodders · 8 Dec 2007 at 19:44

Whats shown on first boot up??

Cob · 8 Dec 2007 at 20:08

Do you have a memory remapping option in your BIOS that can be fiddled with?

LizardKing · 8 Dec 2007 at 21:57

XP cant see 4gig, will need either linux or Vista 64 for that im afraid.
Doubt you will notice the difference between 3.4 and 4gb anyway

rodders · 8 Dec 2007 at 22:08

Oh yea, I saw x64 and assumed was vista, lol.

XP is your problem as said above

Phemo · 9 Dec 2007 at 00:55

Why would XP x64 be a problem? From Microsoft:

http://www.microsoft.com/windowsxp/64bit/overview.mspx
http://www.microsoft.com/windowsxp/64bit/facts/top10.mspx

"Windows Professional XP Edition x64 currently supports up to 128 GB of RAM"

mdjmcnally · 9 Dec 2007 at 01:00

Cob said:
Do you have a memory remapping option in your BIOS that can be fiddled with?

Ignore the bit about XP, what they are saying is true only for 32 bit or normal XP. If you have Windows XP 64 Professional then is going to be a memory remap issue, and possibly the graphics taking some memory.

I had this on a Supermicro HD8CE board and was a memory mapping issue. Followed what said on the forum and was fixed. Does the initial startup show 4096Mb installed or a lower amount

Just checked my P5W64 WS Pro running XP64 and shows all 8Gb or RAM under System Properties

Tuvoc · 9 Dec 2007 at 10:36

XP X64 is certainly not the problem. I have two machines here using it that see all 4GB with no problems. It actually supports a great deal more memoery than that

McB · 9 Dec 2007 at 14:40

I've just had the same thing this morning, had 4x1024 Geil pc6400 under Vista 64 on a Asus P5W-DH, showing as 3198mb in Vista but cpu-z shows 4096 ?? Will go and have a gander for some memory mapping stuff then in bios... funny I haven't noticed and was definately 4gb showing ebfore, hmph.

Also, now slots 1 and 2 are running at 333mhz instead of 400mhz..

philjayj · 9 Dec 2007 at 14:42

Thanks for all your replies. I fiddled about with the BIOS and changed some memory mapping settings and the full 4GB now appears.

Cob · 9 Dec 2007 at 14:46

RLBUHT said:
Thanks for all your replies. I fiddled about with the BIOS and changed some memory mapping settings and the full 4GB now appears.

Good stuff

gurusan · 9 Dec 2007 at 15:11

LizardKing said:
XP cant see 4gig, will need either linux or Vista 64 for that im afraid.

Incorrect. He's running XP x64 which can recognize much more than 4gb

philjayj · 9 Dec 2007 at 18:21

Just one other thing, now that the 4GB is installed, it seems a lot slower on start up. Is a recognised problem, is it normal etc?

Thanks

Phil

Aod · 9 Dec 2007 at 23:48

RLBUHT said:
Just one other thing, now that the 4GB is installed, it seems a lot slower on start up. Is a recognised problem, is it normal etc?

Thanks

Phil

i've found XP x86-64 to startup faster with 4GB than with 2 or 3.
i've also found it to startup faster than XP x86!