Windows XP machine does not recognize 4GB Ram

By chris.praveen ·

I'm running with this problem all the time from upgrading memory.

I built my own system, initially this was the config...
Intel D945GCNL Motherboard
Intel Core 2 Duo E4600 @ 2.40 GHz Processor
1 x 2GB RAM
512MB nvdia Card
Win XP 32 Bit

Thought of going for higher memory and installed 2 more Gig of RAM
But in my computer properties, it gave me only 2.49GB instead of 4GB RAM,

Then i upgraded to Win XP X64
And i still faced the same 2.49GB of RAM.

Recently i've upgraded to ASUS P5KL AM/PS motherboard that supports 4GB RAM due to the reason the my old one doesn't support 4GB

But now i see 3.00GB of RAM.. I just can't understand how these structure is....

I could not get the whole 4GB of RAM utilized..

Someone pls help.

This conversation is currently closed to new comments.

Thread display: Collapse - | Expand +

All Answers

Collapse -

WinXP x32 can not USE 4GB of RAM

by ThumbsUp2 In reply to Windows XP machine does n ...

While your first MB will support installing 4GB of RAM, the upper 1GB (approximately) is reserved for use by the graphics (if I remember correctly), so Windows XP 32bit only makes about 3GB (usually 3.25GB) available to use.

Not sure why the x64 OS doesn't show it all though. Could be you've got mis-matched RAM, since you purchased it in two batches. Did the 2nd purchase exactly match the 1st purchase?

Collapse -

RE: WinXP x32 can not USE 4GB of RAM

by chris.praveen In reply to WinXP x32 can not USE 4GB ...

Ya i did,

Both the memory are from transcend and has got same bus speed and DDR2...

Collapse -

Your unspecified 512MB Nvidia may have 'TurboCache' ...

by OldER Mycroft In reply to Windows XP machine does n ...

There is a chunk of Nvidia graphics card models that use what is called TurboCache.

Basically it was a clever marketing ploy whereby, without breaking the law (by the use of inferred specification) the RAM quoted as being on your graphics card was actually a combination of the RAM actually fitted plus a sizeable chunk of system RAM. Depending on WHICH model number your Nvidia graphics card has, will determine whether this sharing of RAM is the problem, and to what extent.

Check for your specific Nvidia card here:

Collapse -

bus addresses

by balge In reply to Windows XP machine does n ...

some of the memory addresses are used by eg PCI bus, as all devices on the bus (eg PCI cards) have to have an address which leaves less memory for windows therefore shows less than 4Gb

Collapse -

"Simples" ??...

by OldER Mycroft In reply to bus addresses

You don't happen to have a pencil neck and resemble a Meerkat, do you ?

Collapse -


by balge In reply to "[i]Simples[/i]" ??...
Collapse -

32 BIT OS and Chip-Set Limitations

by TheChas In reply to Windows XP machine does n ...

Before I go into details, does ASUS offer a 64 BIT specific driver package for your motherboard? If not, even with the 64 BIT version of XP installed, you may not get 64 BIT addressing.

Unless your motherboard fully supports 64 BIT memory addressing, and has 64 BIT mode drivers, you may run into the same memory limitations as a 32 BIT OS.

The reason for the memory limitation is that there is a memory address limitation for ALL 32 BIT operating systems and 32 BIT motherboard chip-sets.

While it is true that a 32 bit system can address 4 GB of RAM, and many 32 BIT motherboards allow you to install 4 GB of RAM, it is not possible for ANY 32 bit motherboard or operating system to allow the use of all of the installed RAM.

The upper addresses of RAM are reserved for bus and hardware addressing. A minimum of 500 MB is reserved for a simple system. A gaming system with high end video and sound cards can require that up to 1.5GB of address space be reserved for the hardware.

Keep in mind that your memory is not lost. Windows can only report memory that it can address and use.

When this issue first started to appear, the BIOS on most motherboards reported the "usable" memory. In order to reduce complaints, the motherboard manufactures changed the BIOS to show the installed Memory.

The complaints then shifted to Microsoft. When Microsoft released Vista SP1, they changed how Vista reported memory so that the normal system properties screen showed the installed RAM and not the usable RAM.

The only "fix" for the 4GB RAM limit is a full 64 BIT motherboard with a true 64 BIT operating system.


Related Discussions

Related Forums