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Installed 4gb of RAM memory, but BIOS says only 2.5gb are usable

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December 7, 2011 8:10:45 PM

Hi.
I recently brought a memory upgrade for my nice old computer, to upgrade it to 4gb. (I bought two 2Gb memory crads)
The BIOS (as well as the OS) recognize that I have 4gb RAM installed, but list only 2.5gb as usable! :pfff: 

I want to be clear- this is not an OS problem. I'm runnning Windows 7 Ultimate x64. And the problem starts at the BIOS level.

I've done a lot of research, it I think the problem might be that my motherboard's chipset will use part of the memory address for other uses- such as graphics card memory, and BIOS memory and so forth, but I don't think this should add up to 1.5 gigs!

Please help me...
Here is my system spec:

Motherborad: ASUS P5VD2-MX
CPU: Intel Core2Duo 6300 @ 1.86GHz
Chipset (I think this is a chipset): VIA P4M890
Memory: 2X Kingston 2GB (for a total of 4GB) DDR2 533, PC2-4300
Graphics: Nvidia Quadro FX 570, 256Mb
Sound: Sound Blaster Audigy
PCI expansion card for 4xUSB and 3XFirewire 400
2xSATA drives
DVD Burner
OS: Windows 7 Ultimate x64

Thank You
December 7, 2011 8:50:22 PM

Ok i do not no the exact name of the option in bios but i think there is something called memory configuration protection.that limits ur memory see if that works
December 9, 2011 6:37:48 PM

Hi, I'm affraid I didn't see any such option or anything remotley simillar to it.
I scoured through the BIOS settings, read the manual (which was useless), upgraded the BIOS to the latest version... Nothing there...

The bios is Phoenix-AwardsCMOS BIOS, the update is 1017.which was released in 2007...
http://support.asus.com/Download.aspx?SLanguage=en&m=P5...

Any other ideas? Anybody? I'd really appreciate any help on this...
Related resources
December 9, 2011 8:19:32 PM

Ok after doing some research it appears that ur board only supports up to 2gb so it is a board limitation
December 10, 2011 5:50:09 PM

dayto11 said:
Ok after doing some research it appears that ur board only supports up to 2gb so it is a board limitation


Thank you for your reply, though I'm not quite sure which sources you're going by. I don't think you're correct.

For one thing, the board shows I have 4 gigs installed, 2.5 of which are usable (so already more then the 2gb limit you suggested).

Secondly, the motherboard guide specifically says that the motherboard's limit is 4gigs:
Specifications: Memory: 2 x 240-pin DIMM sockets support up to 4 GB ofDDR2 533/400 unbufferred non-ECC memory

Source: Motherboard Guide (page 10)
http://dlcdnet.asus.com/pub/ASUS/mb/socket775/P5VD2-MX/...

December 12, 2011 8:14:13 PM

er_ouz said:
That's the wrong board. Mine is P5VD2-MX.
No "SE" at the end.
Here is the link:
http://www.asus.com/Motherboards/Intel_Socket_775/P5VD2...


o i am very sorry about that could u maybe screen shot ur bios?
cause we know for a fact its not ur os we know its not ur dim slots becasue its reading the ram hmmmm it has to be something in the bios so thats my only idea
or maybe.... reset bios i dont know if that will help but thats my only idea other than listed above
December 15, 2011 12:04:17 PM

dayto11 said:
o i am very sorry about that could u maybe screen shot ur bios?
cause we know for a fact its not ur os we know its not ur dim slots becasue its reading the ram hmmmm it has to be something in the bios so thats my only idea
or maybe.... reset bios i dont know if that will help but thats my only idea other than listed above



Hi dayto11
The Bios was recently reset after a failed oveclocking attempt (this was before I installed the new memory, and I'm positive it's unrelated). It is also the latest BIOS update available from ASUS.
Here is a link to an ImageShack album with 11 screen shots from my BIOS. I wasn't able to find anything relevant in the BIOS myself:
http://imageshack.us/g/31/09122011236.jpg/
December 15, 2011 8:08:35 PM

Ok after looking at the screen shots: top performance what does this do mabey try turning off? And another thing it says that just under 2 gigs is being used as cache i dont exactly know how to fix but mabey 1.5 gigs is being used by parts around ur system thats all i can think of sry i cant figure out the issue.
January 14, 2012 5:12:54 AM

er_ouz said:
Hi.
I recently brought a memory upgrade for my nice old computer, to upgrade it to 4gb. (I bought two 2Gb memory crads)
The BIOS (as well as the OS) recognize that I have 4gb RAM installed, but list only 2.5gb as usable! :pfff: 

I want to be clear- this is not an OS problem. I'm runnning Windows 7 Ultimate x64. And the problem starts at the BIOS level.

I've done a lot of research, it I think the problem might be that my motherboard's chipset will use part of the memory address for other uses- such as graphics card memory, and BIOS memory and so forth, but I don't think this should add up to 1.5 gigs!

Please help me...
Here is my system spec:

Motherborad: ASUS P5VD2-MX
CPU: Intel Core2Duo 6300 @ 1.86GHz
Chipset (I think this is a chipset): VIA P4M890
Memory: 2X Kingston 2GB (for a total of 4GB) DDR2 533, PC2-4300
Graphics: Nvidia Quadro FX 570, 256Mb
Sound: Sound Blaster Audigy
PCI expansion card for 4xUSB and 3XFirewire 400
2xSATA drives
DVD Burner
OS: Windows 7 Ultimate x64

Thank You



Try reinserting/ change slots of the RAM. Mine has 2 1 gb RAM but BIOS and Windows reports it has only 1 gb. The first try of reseating the RAM, BIOS reported 1.5 gb. After changing slots, it now reports the full 2 gb.
January 14, 2012 3:10:22 PM

joeysp said:
Try reinserting/ change slots of the RAM. Mine has 2 1 gb RAM but BIOS and Windows reports it has only 1 gb. The first try of reseating the RAM, BIOS reported 1.5 gb. After changing slots, it now reports the full 2 gb.


I'll give it a try, even though they're both the same make and brand of memory cards, but at this point i'm not scuffing aany suggestions...
I'll tell you how it goes.
Thank you.
January 20, 2012 1:45:40 AM

er_ouz said:
I'll give it a try, even though they're both the same make and brand of memory cards, but at this point i'm not scuffing aany suggestions...
I'll tell you how it goes.
Thank you.





Any update? I'm having the same issue.
February 2, 2012 2:34:50 PM

Didn't work.
Tried switching between the two memories, nothing happened.
Aslo tried removing PCI extension cards (Sound Blaster Audigy sound card and a USB/firewire card) with no difference in the ammount of usable memory shown on the BIOS.
January 3, 2013 12:05:30 PM

wish i had read this before i bought 2 sticks of 2gb ram.
i had read the asus manual for the p5vd2-mx mobo and there it says 4gb is max. so i am very disappointed that bios & windows 7 (64bit) only sees 2.5gb.

i am also surprised that even if its true that 2gb is the limit, then why is an extra 0.5gb recognised?

did anyone find a solution or are we stuck with a 2.5gb ram limit?
January 3, 2013 2:48:27 PM

actually,

i have just taken out the second 2gb ram stick and replaced it with a 1 gb stick (so the motherboard i have which is asus p5vd2-mx-se, now has 1x1gb and 1x2gb installed)
and now both BIOS & windows7 recognise 3gb of ram.

so 2gb is certainly not the max. and now the question is why is the second stick of ram (2gb) not recognised as more than 0.5gb (ie. giving 2.5gb in total)?

by the way,
the 1 gb stick is Hynix
and the 2 sticks of 2gb ram are both Kingston kvr800d2n6\2g.

any thoughts, anybody?
March 1, 2013 4:50:01 PM

Hello

Maybe it's a bit late but I have the same problem. I wrote to my manufacturer's board and they replied me that the problem could be the board's chipset VIA

So I guess that there's no solution despite the fact that the manual says that the board supports 4 gb
April 12, 2014 11:22:31 AM

Old post.. but many older mobos supported 4GB of ram and had early x64 CPUs..the problem was the mobos/bios had problems mapping hardware above the 4GB limit... so even though Windows could us Terabytes of physical memory, and your board allowed 4GB... most likely your video card was using up 1 to 1.5GB of your memory.

It's actually the BIOS' job to move anything hw related out of the address space of physical memory.. I had an older dell once.. it had an early 64bit cpu and it could handle up to 1GB x 4 worth of memory... evenwith a 64bit OS installed the BIOS would only move hardware up to around 5GB... If I used a 1GB video card, I got just about 4GB of memory.. if I used a 2GB card... I'd get 3GB of memory... eventually dell released a bios update which moved all hardware in that machine up to the 8GB mark.

!