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Giga-Byte motherboard is not working properly with a memory of 4GB

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July 18, 2009 4:09:28 AM

Hello, guys!


I’ve got a GA-945GCM-S2C Giga-Byte motherboard whose instructions manual indicates that it is able to work properly with a memory of up to 4GB. Though this motherboard is really
working with a 4 GB memory (2 modules of 2GB DDR2 667MHZ memory size) it is indicating a capacity of up to 3,4 GB.



Can anybody explain to me why this is happening?

Any kind of help is welcome.

Norberto.
a c 177 V Motherboard
a b } Memory
July 18, 2009 4:18:35 AM

Let me venture a guess - you're running a 32 bit (x86) operating system, right? Thirty two bit OS can only address 4GB of physical addresses; some of your hardware (most notably, your video card) needs to 'memory map' an access area for the OS to communicate with the hardware; an area thus 'mapped' cannot also be used for storage by the OS, as it's physical addresses are excluded - thus the 3.4 GB 'visible' inside the OS; moving to a 64 bit OS, such as Vista x64, or Windows7x64 will 'cure' this problem - my OS 'sees' the whole installed 8GB...
a b V Motherboard
a b } Memory
July 18, 2009 5:20:19 AM

Yeah, the problem is that you're using a 32 bit OS without PAT support. If your using XP or Vista 32-bit thos OSs can only use 4GB of addressable memory. First it has to set aside addresses for your devices, most notably the video card, so the more devices and vRam you have, the less addresses there are for your main memory. Even though you got 4GB, windows can only communicate with 3.4GB because that's all it has addresses for.
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a c 156 V Motherboard
a b } Memory
July 18, 2009 12:39:13 PM

If your BIOS sees the whole 4 GB of RAM (I am pretty sure it does), you do not have a hardware problem.
July 18, 2009 4:48:18 PM

I use Windows Vista 64, Bios does not detect 4GB, only 3,4 GB.

Thanks,
Norberto
a c 177 V Motherboard
a b } Memory
July 18, 2009 6:22:36 PM

I will research further; that is an old motherboard - a whole generation of motherboards were limited to thirty-two physical address lines from their CPUs, which has the same effect as the 32 bit windows problem; there are still devices that operate through 'mapped' memory; but, in this case, the actual mapping is done in hardware, rather than in software, as is the windows case... Unfortunately, the results are the same - you will only 'see' some incremental amount less than is physically present in your board. These boards typically will not accept more than 4GB of RAM, and will not benefit from a 64 bit OS, as the devices cannot simply be 're-mapped' in software, as the actual physical locations are 'used up'!
August 12, 2009 4:56:42 PM

With the Intel 945 chip set I know the Patriot memory doesnt work properly, It was stated in the specifications on the memory. I dont know what other brands dont work with that chip set. Good Luck.
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