Have 4Gigs but says I have 2.5Gigs

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akaiello

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Aug 23, 2007
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I just upgraded from 2G’s to 4G’s of Kingston 667, all 4 the same memory, but windows only shows 2.5G’s. I have Windows XP not sure if its 32 bit or 64 bit. After reading what “Scotteq” posted on another post , it seems that 2.5G’s is what it should being saying. Just wanted to know if my system will be using the 4G’s or just use the 2.5G’s or do I need to upgrade my BIOs. Any help would be great. Thanks
 
I agree. A 32-bit OS should show at least 3GB, not 2.5GB. My big question is what video card you are using? If it's integrated, that might explain why it's showing only 2.5GB instead of 3GB.
 
I have the ATI Radeon x300se,its a old card=(. But on the 19th I am going to buy a HD3870. Wow, never thought of the card messing with the ram.
 
I have the same problem, if it is a problem, with a recent build for my parents:
q6600
Asus P5B vanilla
4 gigs Patriot
8600GT 512 MB
WindowsXP 32bit

Only showing 2,5 GB RAM. Memory remapping and other BIOS options don't help...
 
Thanks for the info, I will see what happens when the new card comes. If not changes happen might try and get XP64. Thanks again.
 
There are too many PCIe devices on your mainboard, which each will deduct 250MB from your main memory...
try disabling some onboard devices (such as onboard LAN) and see if you can regain some part of the main memory...
 
If you are looking up your RAM on >my computer/system properties.... that RAM will be less if you have shared memory being dished out all over the show a few times on XP my pc has shown 768mb of RAM instead of 1024mb
 
: Will my system recognize the maximum upgrade?

A: Possibly

How much memory your Windows OS will recognize depends on which version of Windows you are running. 32-bit versions of Windows will see (and utilize) only 3GB or 3.5GB. To utilize more memory, install a 64-bit version of your OS. More information about OS memory maximums can be found at http://www.crucial.com/kb/answer.aspx?qid=4251.

This is from the Crucial website. If you go there and scan your computer these FAQ may help solve your problem. It help me with with a similar problem. As others said your system may use .5 gb of RAM and it might not show up on your system check.
 
This is a Windows 32 bit limitation.
First check your motherboard. Many motherboard can only recognize 3GB.
If your motherboard supports 3-4GB, then you may need to modify your Windows system files in order to see beyond 3GB.
 


If you have an x300 series card, you should see more then 2.5GBs. These cards had at most 256MBs of memory. Add in other things like I/O, and you should see around 3GBS, probably more. If you know what you're doing, you can go into the bios and disable anything you aren't using.

EDIT: Forgot to mention, you subtract the "cache" amount from 4GBs, not 3.5GBs. A 32bit OS assigns RAM starting with memory address 00000000 and works it way up, while I/O and caches start at FFFFFFFF and works its way down. FFFFFFFF is equal to 4GBs, not 3.5GBs
 
Thanks for all the help! I have tried taking one of the sticks out to see if any changes occurred. Nothing changed still 2.5gigs; do you think one of the sticks was DOA? As for my graphics card it has 128MB DDR video memory, just ordered ATI 3870 should be here on Monday or Tuesday. Not really too confident with my BIOs skills, a little scared to go into them. I was trying to find what key/keys to press to access BIOs but, never had enough time. Pressed pause/break key to try and slow boot up down, but then my screen went out =(, so I stopped messing with the BIOs. I emailed ECS to see if they had any patching to give me, I‘ll keep you guys updated, and try to get into my BIOs. Thanks again for the help.
 
Ok, let me try to explain this good enough. A computer uses two bits, 1 and 0. If you have 32 of these, then you have 2^32. This comes out to 4GBs. As I said, the OS assigns physical ram from 00000000 and up. (this is the hexadecimal value of writing it.) The OS however needs to read/write information to the video card, or get information from the harddrives, etc. The video cards memory is assigned from FFFFFFFF on down. The more memory your video card and other devices have, the less memory address space is available for your physical. There simply isn't enough address space.

As I said, your video card is rather low end. 128MBs isn't very much memory, so it wouldn't take up very much address space. (as I understand things, it should only be taking up 128MBs of address space.) Along with everything else in your system, it shouldn't take up more then 1GB, so you should see 3GBs+, not 2.5GBs. Depending on what else is in your computer, there might not be any problem at all.
 
Ok, sorry this took so long but I went into my BIOS and found what my memory was. Seems as though the mobo is also seeing 2.5G.
Total Memory= 2621440k=2.5G
Base Memory 640k
Extended Memory=2620416k=2.48G
Current MRC Version 6.4
Current FSB Frequency 200MHz
Current DRAM Frequency 333MHz
Memory Clock [AUTO]

If you need any other info tell me know.
Thanks
 
The limitation of 4GB address space was introduced in SP2

bios might display the useable amount of ram. If your hardware support more than 4G and memory remapping, you could try and enable remapping to Test if bios will report it all (just as a test, your windows cannot use the remapped ram)
 
Vast majority of people use 32-bit OSs purely for the convenience as u dnt need to hunt down 64-bit drivers which are usually behind the 8-ball as far as features go and often unstable. and thats the limiting factor.
your OS.

because ur running 32 bit XP that limits the RAM that ur comp can access to 4gb. The recommendation is to use 3gb or less of ram. This is because large chunks of memory in the 3gb to 4gb section are reserved for "memory-mapping devices" and scarily this also includes the 128MB to 1GB of memory installed in your graphics card.

If you use a 256MB graphics card, then 256MB of the memory between 3gb and 4gb will be unavailable for you to use, ie. you will only see 3.75GB of usable memory.
For those with less than 4gb of RAM its not eating into that memory, as these devices are mapped: it's virtual address space - your PC thinks it's there but it isn't really, until you actually put that much RAM in. Confused yet?

Now moving onto 64bit OS doesn't change that one bit. You'll get roughly the same amount of available RAM using 4gb of memory under 64-bit as under 32-bit OSs - no advantage there. However, 64-bit allows you to go further than 4gb, so you can start ramping it up again. The price of 2gb memory modules and the support of the motherboard to cater to larger RAM sizes not withstanding.

Looking forward it will be one of those facts we take for granted as history shows these memory maps don't get removed: we just move on past them. So, in a few years time, you'll be installing 8gbof RAM with your 1gb video card and you'll only get 7GB to actually use.

As rule of thumb, its recommended 2gb or 3gb for those building a PC. Seeing as 32-bit vista will limit you to 3.12gb of memory anyway, you wont feel ripped off *as u undoubtedly might be*, and it'll save a bit of money on memory you can't use.

For those going 64-bit... good luck.
 


I'm thinking you might need a bios update. The bios should see the full four gigs. Try running with only the new ram, make sure both sticks are good. (just pull the original ram.) Assuming they run fine in the slots they've always been in, I'd look for a bios update.
 


So? A 32bit OS should see more then 2.5GBs. At this point, we aren't even talking about the OS, but the BIOS. That certainly should see more then 2.5GBs. If the bios is only seeing 2.5, thats why the OS sees 2.5 and not 3.2-3.5GBs.
 
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IF YOUR COPY OF WINDOWS IS 32 BIT VERSUS 64 BIT IT WILL NOT BE ABLE TO USE 4 GIG OF RAM. IT'S THE WAY THINGS ARE. DONT BOTHER. IT WONT WORK. PLEASE FORWARD THIS TO EVERYONE IN YOUR ADDRESS BOOK. LEAVE IT WRITTEN ON POST-IT NOTES IN THE SUBWAY. OPEN YOUR WINDOW AND YELL IT OUT. CUT IT INTO YOUR LAWN. TATTOO IT ON YOUR BACK. I HAVE A DREAM... A DREAM WHERE PEOPLE GOOGLE THIS QUESTION BEFORE ASKING IT THE 47 BILLIONTH TIME.

IF YOUR COPY OF WINDOWS IS 32 BIT VERSUS 64 BIT IT WILL NOT BE ABLE TO USE 4 GIG OF RAM. IT'S THE WAY THINGS ARE. DONT BOTHER. IT WONT WORK. PLEASE FORWARD THIS TO EVERYONE IN YOUR ADDRESS BOOK. LEAVE IT WRITTEN ON POST-IT NOTES IN THE SUBWAY. OPEN YOUR WINDOW AND YELL IT OUT. CUT IT INTO YOUR LAWN. TATTOO IT ON YOUR BACK. I HAVE A DREAM... A DREAM WHERE PEOPLE GOOGLE THIS QUESTION BEFORE ASKING IT THE 47 BILLIONTH TIME.

IF YOUR COPY OF WINDOWS IS 32 BIT VERSUS 64 BIT IT WILL NOT BE ABLE TO USE 4 GIG OF RAM. IT'S THE WAY THINGS ARE. DONT BOTHER. IT WONT WORK. PLEASE FORWARD THIS TO EVERYONE IN YOUR ADDRESS BOOK. LEAVE IT WRITTEN ON POST-IT NOTES IN THE SUBWAY. OPEN YOUR WINDOW AND YELL IT OUT. CUT IT INTO YOUR LAWN. TATTOO IT ON YOUR BACK. I HAVE A DREAM... A DREAM WHERE PEOPLE GOOGLE THIS QUESTION BEFORE ASKING IT THE 47 BILLIONTH TIME.

IF YOUR COPY OF WINDOWS IS 32 BIT VERSUS 64 BIT IT WILL NOT BE ABLE TO USE 4 GIG OF RAM. IT'S THE WAY THINGS ARE. DONT BOTHER. IT WONT WORK. PLEASE FORWARD THIS TO EVERYONE IN YOUR ADDRESS BOOK. LEAVE IT WRITTEN ON POST-IT NOTES IN THE SUBWAY. OPEN YOUR WINDOW AND YELL IT OUT. CUT IT INTO YOUR LAWN. TATTOO IT ON YOUR BACK. I HAVE A DREAM... A DREAM WHERE PEOPLE GOOGLE THIS QUESTION BEFORE ASKING IT THE 47 BILLIONTH TIME.

IF YOUR COPY OF WINDOWS IS 32 BIT VERSUS 64 BIT IT WILL NOT BE ABLE TO USE 4 GIG OF RAM. IT'S THE WAY THINGS ARE. DONT BOTHER. IT WONT WORK. PLEASE FORWARD THIS TO EVERYONE IN YOUR ADDRESS BOOK. LEAVE IT WRITTEN ON POST-IT NOTES IN THE SUBWAY. OPEN YOUR WINDOW AND YELL IT OUT. CUT IT INTO YOUR LAWN. TATTOO IT ON YOUR BACK. I HAVE A DREAM... A DREAM WHERE PEOPLE GOOGLE THIS QUESTION BEFORE ASKING IT THE 47 BILLIONTH TIME.

IF YOUR COPY OF WINDOWS IS 32 BIT VERSUS 64 BIT IT WILL NOT BE ABLE TO USE 4 GIG OF RAM. IT'S THE WAY THINGS ARE. DONT BOTHER. IT WONT WORK. PLEASE FORWARD THIS TO EVERYONE IN YOUR ADDRESS BOOK. LEAVE IT WRITTEN ON POST-IT NOTES IN THE SUBWAY. OPEN YOUR WINDOW AND YELL IT OUT. CUT IT INTO YOUR LAWN. TATTOO IT ON YOUR BACK. I HAVE A DREAM... A DREAM WHERE PEOPLE GOOGLE THIS QUESTION BEFORE ASKING IT THE 47 BILLIONTH TIME.
 
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