4 gig memory installed only 3 showing up

**Anilrgowda** · 31-Jul-2007, 02:41 AM

PLEASE Help running vista ultimate toshiba Satellite A105-S4334 4 gig memory installed, only 3 showing up. How can I make all 4 useable?

**Anilrgowda** · 31-Jul-2007, 02:42 AM

I'll try to explain in simple terms:-
There is a limitation of a 32 bit OS/some motherboards that prevents the addressing of more than 4Gb of memory - Hoevers even this 4Gb limit cannot be all used for system memory as the PC needs to use some of this address space to control stuff like the PCI bus etc , so some of this address space is used and cannot be used to acceess memory. Therefore if you install 4Gb - some of that 4Gb will not be addressable. This normally results in only 3.25-3.5Gb being actually available for use.

31-Jul-2007, 02:41 AM	#1 (permalink)
Anilrgowda Administrator Posts: 18,715 Join Date: Jan 2006 Rep Power: 10 IM:	4 gig memory installed only 3 showing up PLEASE Help running vista ultimate toshiba Satellite A105-S4334 4 gig memory installed, only 3 showing up. How can I make all 4 useable?

31-Jul-2007, 02:42 AM	#2 (permalink)
Anilrgowda Administrator Posts: 18,715 Join Date: Jan 2006 Rep Power: 10 IM:	Re: 4 gig memory installed only 3 showing up I'll try to explain in simple terms:- There is a limitation of a 32 bit OS/some motherboards that prevents the addressing of more than 4Gb of memory - Hoevers even this 4Gb limit cannot be all used for system memory as the PC needs to use some of this address space to control stuff like the PCI bus etc , so some of this address space is used and cannot be used to acceess memory. Therefore if you install 4Gb - some of that 4Gb will not be addressable. This normally results in only 3.25-3.5Gb being actually available for use.

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