arkadaşlar Dell Optilex GX270 model pc...teknik dökümanlarında maksimum ram belleğinin 4gb. olduğu yazıyor...4 adet ram slotuna 1 gb lık kingston (dördüde birebir aynı ram) ları takıyorum biostan görüyor...ancak XPpro tr + sp2 de kesinlikle 3 gb. görüyor...ram slotlarını da ram leri de tek tek denedim...işin ilginci everest tek tek slotlar da ki ram leri 1 gb. olarak görüyor ancak işletim sistemi görmüyor...
Cevap:
Xp:En çok 4 gigabayt (GB) RAM ve iki simetrik mikro-işlemci desteği sunmaktadır.
http://support.microsoft.com/kb/888137/en-usAfter you upgrade to Microsoft Windows XP Service Pack 2 (SP2), the amount of memory that is reported in the System Properties dialog box or by the System Information tool (Msinfo32.exe) has changed. This symptom occurs if the following conditions are true:
Your Windows XP-based computer has 4 or more gigabytes (GB) of RAM.
Your Windows XP-based computer is using Physical Address Extension (PAE) mode.
Note PAE mode is enabled by adding the /pae parameter to your Boot.ini file in the root folder of your system drive.
For example, before you upgrade to Windows XP SP2, the System Properties dialog box may report approximately 3.87 GB of RAM. The System Information tool may report that the total physical memory is approximately 3,540.00 megabytes (MB). After you upgrade to Windows XP SP2, the System Properties dialog box may report approximately 3.12 GB of RAM, and the System Information tool may report that the total physical memory is approximately 2,770.00 MB.
Note If you disable PAE mode on a Windows XP-based computer that has 4 GB of RAM, the System Properties dialog box may report approximately 3.12 GB of RAM, and the System Information tool may report that the total physical memory is approximately 2,710.00 MB. The same values are reported after you upgrade to Windows XP SP2
yani:
C:\boot.ini dosyasını açarak multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /noexecute=optin /fastdetect /PAE
sondaki PEA ilavesine dikkat ediniz bu sekilde xp 4 GB ram i sorunsuz görebilir ( eğer işlemciniz PEA (PAE=physical address extension) yi destekliyorsa)
ayrica PAE nin registrydeki yeri:
HKLM\SYSTEM\CURRENTCONTROLSET\CONTROL\SESSIONMANAGER\MEMORYMANAGEMENT\PhysicalAddressExtension
konuyla ilgili güzel bir aciklama:
ALINTIDIRPCI devices always "steal" RAM, even on a system with less memory. You just don't notice because PCI devices are usually sitting at an address beyond the end of physical memory.
Remember, 32-bit processors have a 4GB address space (from 0x00000000 to 0xFFFFFFFF). If you have 1GB of RAM, any address above 0x40000000 is free.
Most PCI devices are memory mapped. This means they are mapped to a memory address. If the CPU wants to talk to your Ethernet Card, it reads and write to a certain memory address, which happens to be where your Ethernet Card is listening.
The memory address that your device uses is determined by the BIOS at boot time (although the operating system can remap the device later). The device can claim anywhere from 0 to 6 memory regions, and they can be just about any size.
Exactly how many memory regions, and their size can vary gratly by the device. Ethernet cards tend to use very little. Graphics cards, however, can use a lot. Grpahics cards have a lot of onboard RAM, and that RAM can be often addressed by the PCI bus. If you have a video card with 128MB of RAM, it may claim a 128MB window on the PCI bus. Some high-end SCSI controllers claim a lot of address space as well.
If you want to see the addresses claimed on your system, go to Control Panel - System - Hardware - Device Manager. Click View - Resources by Type. Expand the memory selection. You should see all the memory-mapped devices in your system, and what they claim.
Since you have a 4GB limit, your system needs to make all of the devices, and your RAM fit. That's why you see less RAM. If it didn't allocate enough address space for your hardware, the device wouldn't work (which would be really bad). So, it does the safe thing, and give you less ram.
You can do one of the following:
- Live with the limit. Maybe sell the spare 1GB module.
- Get a CPU with PAE. PAE give you a 36-bit address space. This lets you use RAM at addresses above 0xFFFFFFFF. You will need to use the "/PAE" switch during bootup.
- Switch to a 64-bit CPU. You'll need a 64-bit operating system.
One little tidbit. Most PCI devices are 32-bit, so they have to live at an address below 0xFFFFFFFF. There are also 64-bit PCI devices that can be mapped to addresses above 4GB, but they're another issue entirely.