Bios ram limits

April 21, 2009 at 22:08:29
Specs: Windows XP PRO
I understand the 4GB Xp Limit, however, i'm only getting 2.47. My Intel Mobo supports 4g, shows the 4 slots with 1024, and total ram of 4096. But after I exit and save, the boot before Windows starts shows only 2536mb of ram. I've updated my bios to the latest version. Anyone with ideas how to get my extra gig of ram to work. /chad in houston

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April 21, 2009 at 22:54:53
Are you using only one stick RAM?
Or more than one RAM.

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April 22, 2009 at 02:42:27
download memtest86 and set up the boot disc then boot to the application and see what memtest says after about 12 hours. Any error reports at all shows faulty ram and it should be replaced.

Change Is Good

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April 22, 2009 at 05:35:01
I am using 4 1gig sticks set up in dual mode. the matches are in dimm 0 and 1 channel a.... and dimm 0 & 1 channel b

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April 22, 2009 at 06:43:54
"I understand the 4GB Xp Limit"

I don't think you do. It's not an XP issue, it's a 32-bit OS issue. There's 4GB of virtual address space (VAS) available & that 4GB must be shared by ALL the hardware components that require memory mapping. The more hardware you have that requires it, the less room there is for the actual RAM to use, therefore less RAM will be recognized by the OS. The RAM amount *usually* drops to somewhere between 3.0 - 3.5GB, but it depends on the hardware configuration. Many systems using ASUS boards tend to drop to 2.93GB, sometimes less. If you have a 1GB video card or two 512MB video cards in SLi or Crossfire, that 1GB is deducted from the VAS.

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April 22, 2009 at 07:44:38
Yes, I think I get the Xp 32 bit issue, but I though Id at least have up to 3.4 gig left over instead of the 259540 Physical Memory. I realize i won't get the whole 4.0 but i was hoping for at least more that 2.59... What I don't understand is why the bio tells me i have 4096m then after it starts it's bootup, before getting into Windows, it tells me 2536m. I've rearrange the order of the sticks, i've only used two at a time...they all give me 2g just fine so i know they're all working.

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April 22, 2009 at 08:06:22
It sounds like you still don't understand all that jam just explained above. Some graphics cards will have some on
board RAM and still use system RAM. You MAY have an option to adjust the amount of system RAM being used.

The issue is not a WinXP issue.

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April 22, 2009 at 16:09:46
"Yes, I think I get the Xp 32 bit issue"

"What I don't understand is why the bio tells me i have 4096m then after it starts it's bootup, before getting into Windows, it tells me 2536m"

No, obviously you still don't get it & probably didn't click on the link I supplied or any of the accompanying links. Maybe a copy/paste will help you to understand. Here's a portion of the explanation:

"Current operating systems, such as Microsoft® Windows® XP, can only use a maximum of 4 GB of address space; however, the amount of memory available to the operating system is less than 4 GB. Certain components within the computer require address space in the 4-GB range. Any address space reserved for these components cannot be used by computer memory.

The following components require memory address space:

- System ROM
- APIC(s)
- Integrated PCI devices, such as network connectors and SCSI controllers
- PCI cards
- Graphics card
- PCI Express cards (if applicable)

At start-up, the BIOS identifies the components that require address space. The BIOS dynamically calculates the amount of reserved address space required. The BIOS then subtracts the reserved address space from 4 GB to determine the amount of usable space.

If the total installed computer memory is less than the usable space, all installed computer memory is available for use only by the operating system.

If the total installed computer memory is equal to or greater than the usable address space, a small portion of installed memory is unavailable for use by the operating system."

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April 23, 2009 at 07:31:14
Super Info everyone. Thanks for all your input. I have a better understanding of it all. By removing my 256m video card and switching back to on board video, i noticed the changes you were talking about. I also adjusted the agp size from 256 down to 4 which shows me more for my operating system.

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April 23, 2009 at 14:15:41
If you are using onboard video with only 4MB of system memory your graphics performance is going to be bad.

What is the issue with the amount of usable RAM you had to start. I suggest you reinstall the add in card. Just check the BISO after the card is in to be sure more RAM isn't being used. Leave the onboard at 4MB.

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