Would adding this memory impact performance?

Wabbit

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My main concern is the finicky-ness of dual channel RAM kits. I currently have a MSI P965 Platinum motherboard, currently with a 2 GB Dual Channel kit of SuperTalent DDR2 800 (PC2 6400) RAM. It says the timing is 4-4-3-8 and it is Cas 4, 2.2 volt. ( http://www.newegg.com/product/product.asp?item=N82E16820609026 )

I have another pair of dual channel slots available, and have just been given a 2 GB Dual Channel kit of Kingston HyperX DDR2 800 (PC2 6400) RAM. It says the timing is 4-4-4-12 and it is also Cas 4, 2.0 volt. ( http://www.newegg.com/Product/Product.asp?Item=N82E16820134125 ).

Is this memory compatible for dual channel in two different channel pairs? The main thing that makes me wonder is the different voltages. Also, will adding this memory affect performance?

Thanks for any help!
 

Mondoman

Splendid
Under 32-bit Win XP, the system will only be able to address (and thus use) about 3GB of the 4GB total, due to address space limits under 32-bit OSs. You should be able to get both sets to work togerther at some speed, but it might not be DDR2-800 and/or the rated timings. Use memtest86+ to test the memory setting for stability before trying to run windows.
 

Wabbit

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Ok, so if XP can install 4 GB of RAM, but only recognize 3 GB, then what about Vista 32 bit? It claims to be able to access up to 4 GB, but it is still 32 bit. Anyone know for sure?
 

Mondoman

Splendid
Well, XP can access up to 4GB, but you can only get to 4GB if you don't have any hardware that takes up memory addresses, which is impossible in practice.
Here's a decent article on the Win XP limit:
http://www.hardforum.com/showthread.php?t=1035670

I'm not sure about 32-bit Vista, but since addressing more than 4GB requires not just software (such as drivers), but also hardware to be designed to be more-than-32-bit address-safe, I'm not optimistic.
 

Wabbit

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So would a core 2 duo processor fill the hardware needs for the 4 GB of RAM?
I think it is 64 bit, which I know can handle more than 4 GB or RAM.