Windows XP 64-bit shows less RAM than the amount installed Tags: Ubuntu RAM Windows XP Last response: November 4, 2010 6:11 PM in Windows XP Share alecz20 November 2, 2010 9:01:19 PM Hello This is the system in question: - 64-bit CPU (Intel i5 750) - 64-bit Motherboard (Asus P7P55M) - 64-bit Windows XP - 64-bit Ubuntu 9.10 - 4 GB RAM installed - separate Video Card (ATI Radeon HD 5770 - 1 GB Video RAM) The BIOS, Memtest86+, and Ubuntu, all show 4.0 GB of RAM in the system Windows XP x64, however, shows 3.5 GB of RAM installed. Question: Why is it that only Windows x64 show less RAM, while everyone else shows correct amount? I also HAD Ubuntu 32-bit, and it showed 2.9 GB, so Ubuntu would show the 32-bit limitation. Then I installed Ubuntu 64-bit, and I can see 3.9 GB (for some reason it doesn't show 4.0, but that's minor) Windows XP x64 (YES I am sure it is the 64-bit version) shows 3.5 GB of RAM Memory remapping in BIOS is turned ON, but I don't remember if I turned it on before or after I installed Windows. It was definitely ON before I installed Ubuntu 64-bit. Now if I toggle memory remap ON/OFF, I see that everyone detects only 3.5 GB with memory remap OFF, but with memory remap ON only XP detects 3.5 GB. Note: There is no on-board video on this motherboard, so the argument that memory is reserved for the video-card is invalid. Any ideas? More about : windows bit shows ram amount installed rexter November 4, 2010 4:33:24 AM What service pack do you have? Don't know if you've check this one already. http://en.wikipedia.org/wiki/Physical_Address_Extension... alecz20 November 4, 2010 5:57:27 PM I have Service Pack 1. I don't know what you wanted me to see on that link. The only relevant information is that it says that Windows XP 64-bit (which I have) supports up to 128 GB of RAM. Maybe I'll try to upgrade to a newer service pack (if it exists) Can't find your answer ? Ask ! Get the answer rexter November 4, 2010 6:11:54 PM I gave you the wrong link, anyway there was a discussion on one forum that one person manage to see the RAM corectly by updating to XP SP2. just wondering if you did so already? http://www.microsoft.com/downloads/en/details.aspx?Fami... Can't find your answer ? Ask ! Publish Related resources: ForumLess RAM showing than what is actually installed . ForumWindows /BIOS showing less RAM than is installed .. ForumHelp Ram Showing less than installed ForumIs a 64-bit Windows 7 quicker than 32-bit in itself, as an OS? ForumPrograms use WAY more space than manufacturer's required amount ForumWindows 7 64bit not showing right amount of RAM ForumRAM showing less than installed ForumBudget Build with thoughts of the future for less than $600 ForumMem shows less then installed memory? ForumWin 7 64-bit doesnt use all installed RAM ForumPC & HTPC Combo less than $500 Forum4Gb's ram , showing up as 3.12Gb's in Windows XP ?? ForumSometimes Windows shows I have less RAM ForumBoot screen does not show installed amount of RAM on pc ForumPagefile Size Windows Vista 64-bit with 8GB RAM ForumInstalled althon 64 x2 4800+ and only shows 2.50GB RAM ForumHelp, Vista never uses less than 1GB of RAM ForumPCMCIA slots need more power??? HELP! ForumHelp windows crashing hard and fast ForumWindows xp print spooler alwaz on More resources Read discussions in other Windows XP categories Configuration Customization Drivers Security Video !