jimras Posted July 10, 2008 Report Share Posted July 10, 2008 I recently upgraded my computer and I installed 2 Gig of Memory at the time and all worked fine.I saw on Sunday that Tiger direct had the memory on sale that I just bought a month ago so I bought me 2 more Gigs ($34 after rebate) and installed that too. The motherboard has four slots and now theyare all full. The memory sticks are all the same.....Corsair TWINX PC6400 DDR2 800 MHz ....four 1 Gig sticks.The MoBo will accept up to 16 Gigs of memory, from what I read. It is an Asus M2N-SLI nForce 560 Socket AM2 boardand I am running an AMD Ahtlon 64 X2 6000+ chip at 3GHz and I have XP Pro SP3 for my OS.Now....here's the thing. The BIOS says that there are 4 Gig installed but when I check thru Windows / Control Panel / System / it shows that I have 3.25 Gig of memory. I remember reading that XP Pro could/would use up to 4 Gig of memory so why isn't it showingup there? Is something wrong or out of whack? I would appreciate any help or advise that you experts could offer on this.jim Quote Link to post Share on other sites
Besttechie Posted July 10, 2008 Report Share Posted July 10, 2008 I assume you are running a 32bit version of Windows XP, if that is the case, Windows will not address more than the 3.25GB it is showing. In order for it to recognize the full 4GB of RAM you will need to get a 64bit edition of Windows.B Quote Link to post Share on other sites
jimras Posted July 10, 2008 Author Report Share Posted July 10, 2008 I assume you are running a 32bit version of Windows XP, if that is the case, Windows will not address more than the 3.25GB it is showing. In order for it to recognize the full 4GB of RAM you will need to get a 64bit edition of Windows.BOK then. That makes sense.Thanks BT...appreciate the quick reply.jr Quote Link to post Share on other sites
shanenin Posted July 11, 2008 Report Share Posted July 11, 2008 I found this explanation by the author "AnonymousCoward" on another forum. He(she) did a nice job of explaining it.All major 32bit operating systems can address 4GB of RAM. In fact most can address far more (using technology called PAE that's been available in Intel CPUs for several generations now). This is how Windows Server 2003 Data Center Edition can address 64GB of RAM, even though it's a 32bit OS.Now, for Windows 2000 / XP / Vista, Microsoft has put in a hard coded limit of 4GB of address space. Partly to sell higher end OSes, and also partly because a lot of consumer drivers where never written to cater for addresses beyond the 0xFFFFFFFF boundary and would thus blue-screen the machine (in XP prior to SP2 you could use /PAE to get >4Gb of addresses)OK, so why can Windows only see something less than 4GB of RAM? Because the BIOS allocates some memory addresses to hardware devices that are memory mapped. This includes various video cards, RAID controllers and sundry other devices. How much depends on what the hardware device needs/requests. Those addresses are *not* available to Windows to use to get at memory, and becuase Windows XP / Vista can only use addresses below the 4GB boundary, it can't address that RAM. Quote Link to post Share on other sites
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.