Question : Problem: Bios and windows does not see all my ram

My bios and windows xp will only see 2.68 gigs of the 3 gigs I have installed.

And yet SiSoftware Sandra can see it.

I have the 2 1gig sticks in the same coloured dimm slots and the 512's in the other 2 dimm slots.

The 2.68 seems a strange figure to show up as my video card has it's own 512 mem on the card and so it is not taking any on board memory from that.

I have an ecs pf5 extreme motherboard and can not find anything about the memory in the bios apart from setting the mhz setting.

I have upgraded the bios but this has made no difference

The 2 1 gigs are the same make and the 2 512's are a different make will this make a difference.

I have tried tech at ECS but they never respond to any emails or tech form on the website.

Any info would be a great help.

Answer : Problem: Bios and windows does not see all my ram

callrs - as I noted in my 1st post, this is a well-known issue; and is simply a matter of the restriction caused by a 32-bit address space and the need for the system to reserve space for PCI mapping, interrupts, AGP apertures, BIOS shadowing, PCI I/O addresses, etc.   I wrote a fairly long, much more detailed answer to this a few months ago, but couldn't find it in a quick review of my answers -- I'll look again and MAY post it  (otherwise feel free to scan through my answers and look for it).   The Intel white paper you already found discusses about as much detail as you really need to know -- the key is to recognize that this IS going to happen, and there's nothing you can do about it :-)    On some systems using the /PAE switch will remap and recover some of the memory with the additional 4 address bits; but not all systems work correctly with /PAE, and the extra memory access overhead is not, IMHO, worth the small gain in useable memory in most cases.

alanaldis - Do you have any further questions about this?   It is a shame the motherboard manaufacturers don't make it a bit clearer in their manuals that you won't "see" all of the memory in the upper address space.

By the way, SiSoft is reporting the correct amount:

Note in the "Mainboard" section:
Total Memory : 2.6GB DDR2-SDRAM

In the "Chipset 1" section it shows the 3GB you actually have installed, but this is just reporting the SPD information from the memory modules.