RAM size.

[Tommy L]

I have 4 Gig of ram installed on an Asus P5B. I am running XP 64. Windows says I have 4G ram installed, however, in BIOS Setup utility its saying my System Memory Usable Size is 3072mb.

Which is correct? Do I have a faulty stick?

Thanks,

Tom.

[martincg]

i think these asus motherboards series have problem with newer memory - check version of your bios if it is actual version /with bios fix log in asus website/.

[Matt McDonald]

You need to enable memory mapping in your BIOS (note: this will only work if your system supports more than 4Gb of RAM)

[Tommy L]

You need to enable memory mapping in your BIOS (note: this will only work if your system supports more than 4Gb of RAM)

 

Thanks guys,

Does it matter if Bios only sees 3g when windows sees 4g? Does BIOS 'know' I have a 64 bit OS installed?

Tom.

[Matt McDonald]

Your BIOS doesn't know anything about the OS. The reason that it is reporting less than 4Gb of RAM is because of memory mapping. The system has to allocate some memory addresses for the PCI devices, in doing so the RAM can not use those addresses and the system reports less usable memory than you have installed.

 

If your motherboard supports 4Gb of RAM your system will report less than 4Gb of usable memory. If your motherboard supports 8Gb RAM (anbd you have that much installed) your system will report less than 8Gb of usable memory.

 

I'm awfully sure this is the issue. If you had a bad stick of memory your machine would more than likely be wildly unstable. You can test your RAM using memtest86. If there is anything wrong with your RAM it will report it.