RAM upgrade not recognised in XP
 

I have just upgraded a new HP desktop's RAM which i'm using as a server from 2GB (2 X 1GB) to 6GB (original 2x1 GB + 2X2 GB). In system the RAM is now saying 2.84 GB RAM. Is this a hardware or XP issue? Any ideas how to fix it? The motherboard had black and blue RAM slots. I kept the original 1Gb Dimms in the black slots and put the new 2gb dimms into the Blue slots. The RAM is DDR2 800MHz/PC6400.

Jer

Is it a 64bit OS? 32bit OS will only see 3gb, but will utilise the other 1gb.

What motherboard is in it? some don't accept more than 4gb.

its a 32bit system. it's an HP Compaq dx2450 MicroTower, AMD Athlon 1640B. So it may only use 4GB? if so I can use the 1gb dimms in other machines.

I have just done a search it says upgradable to 4GB.

The system board will accept 4GB of system memory. The operating system can not address 4GB of system memory though.

Memory Limits for Windows Releases (Windows)

Could do, but say if these dimms are 333hrz and you put them in a machine with 800mhz dimms, the computer will limit all of them to the lower speed.

Windows will only address 3.25gb (32bit) of ram and that is what will show up in XP, it is supposed to use the rest, but I don't know how this would be done by the OS or how you would test if it is using it.

<irate geek>
I think the next person that says 32 bit XP can only see 3Gb, or ANY other figure than 4Gb I'm going to slap.

32 bit means it has 32 bit memory addressing, which means 2^32 or 2x2 32 times. Which equals 4Gb. Go do the maths.

The reason you never see the 4Gb when you look in properties is that some of the memory is reserved, mainly by the Video card which maps ITS memory into main RAM.

</irate geek mode>

Ask Dan: What's with the 3Gb memory barrier? gives a great explanation, and why you shoudl wave bye bye to great swathes of main memory when buying a 4870X2 :)