Mixing DDR2 RAM - Asus mobo, Core 2 Quad CPU
No doubt this question has been asked 100 times before, but I am struggling to find a clear-cut answer that fits my case. Besides, it makes a change to be asking, rather than answering, a question in EE.
Here is the background:
I want to build a reasonable spec 64 bit server so I can test Microsoft Windows Server 2008, Exchange, Virtual server, MS-SQL 2008 etc. I have an Asus P5Q Pro mobo and a pair of 1GB memory sticks like this:
Kingston 2GB Kit (2x1GB) DDR2 800MHz/pc2-6400 Hyperx Memory Non-ECC Cl4 2.0V
For the apps I want to install the server will need at least 4GB of memory, possibly more. So rather than just adding another pair of DDR2's like the above, I thought I'd get a pair of 2GB sticks which would then give me the option of mixing both types of memory together to make a total of 6GB of RAM.
The plan is to use an Intel Core 2 Quad Q8300 2.5GHz (FSB 1333MHz) processor which would be purchased along with the new RAM (i.e. the choice is still open). I do not want to overclock anything - reliability is my top priority.
So my questions are:
1. How important is it to match each of the spec items: 800MHz, CL4, 2.0V and the Kingston manufacturer?
2. Is it safe to mix different speed, latency, voltage RAM provided the mobo is just configured for the slowest/lowest?
3. Is there any advantage to matching CPU FSB clock speeds and memory frequency to be in particular multiples (as I have read somewhere)? If so, would it be better to choose DDR2-1066MHz and not using the existing 800MHz sticks?
The memory I was thinking of getting is this (it seems to match the existing in all respects except manufacturer):
OCZ 4GB (2x2GB) DDR2 800MHz/PC2-6400 Titanium Memory Kit CL4(4-4-4-15)
Thanks in advance.
Here is the background:
I want to build a reasonable spec 64 bit server so I can test Microsoft Windows Server 2008, Exchange, Virtual server, MS-SQL 2008 etc. I have an Asus P5Q Pro mobo and a pair of 1GB memory sticks like this:
Kingston 2GB Kit (2x1GB) DDR2 800MHz/pc2-6400 Hyperx Memory Non-ECC Cl4 2.0V
For the apps I want to install the server will need at least 4GB of memory, possibly more. So rather than just adding another pair of DDR2's like the above, I thought I'd get a pair of 2GB sticks which would then give me the option of mixing both types of memory together to make a total of 6GB of RAM.
The plan is to use an Intel Core 2 Quad Q8300 2.5GHz (FSB 1333MHz) processor which would be purchased along with the new RAM (i.e. the choice is still open). I do not want to overclock anything - reliability is my top priority.
So my questions are:
1. How important is it to match each of the spec items: 800MHz, CL4, 2.0V and the Kingston manufacturer?
2. Is it safe to mix different speed, latency, voltage RAM provided the mobo is just configured for the slowest/lowest?
3. Is there any advantage to matching CPU FSB clock speeds and memory frequency to be in particular multiples (as I have read somewhere)? If so, would it be better to choose DDR2-1066MHz and not using the existing 800MHz sticks?
The memory I was thinking of getting is this (it seems to match the existing in all respects except manufacturer):
OCZ 4GB (2x2GB) DDR2 800MHz/PC2-6400 Titanium Memory Kit CL4(4-4-4-15)
Thanks in advance.
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ASKER
If I understood correctly, RAM rated at higher frequencies/voltages makes sense if you intend tweaking settings to get more performance out of it. Since that was not in my plans I decided to go for the safe option and buy some bog-standard Kingston RAM that is listed in the Asus QVL. It was about 10% cheaper than the OCZ too.
When it arrived I was surprised how thin and weedy these new 2GB DIMMs looked compared with the 1GB sticks I already have (from the same manufacturer). There's no heatsink on the new ones and they are about 1/4 or 1/3 of the height. However, they seem to work fine. I have only tried them on their own so far - not mixed the 2x2GB with 2x1GB to get 6GB. I may just abandon that idea now, buy the same again and double up to get 8GB because the applications I want to test use a lot of memory (Exchange server and Hyper-V).
Thanks for the help anyway.
When it arrived I was surprised how thin and weedy these new 2GB DIMMs looked compared with the 1GB sticks I already have (from the same manufacturer). There's no heatsink on the new ones and they are about 1/4 or 1/3 of the height. However, they seem to work fine. I have only tried them on their own so far - not mixed the 2x2GB with 2x1GB to get 6GB. I may just abandon that idea now, buy the same again and double up to get 8GB because the applications I want to test use a lot of memory (Exchange server and Hyper-V).
Thanks for the help anyway.
ASKER
1& 2) You've confirmed what I suspected regarding speed/latency, but your comment about the RAM voltage really surprises me. I have seen more than one reputable source - including Wikipedia - state that there is a standard voltage of 1.8V for DDR2. I assumed that ratings above this relate to the RAM's ability to work at a higher voltage and provide better performance (overclocking of sorts). The BIOS on my mobo also states that 1.8V is the default setting.
From a practical perspective of matching new RAM to old, the details available on the seller's web site don't specify a voltage for that OCZ package. However, the blurb states that "OCZ EVP (Extended Voltage Protection) is a feature that allows performance enthusiasts to use a VDIMM of 2.25V without invalidating their OCZ Lifetime Warranty". So I'm left a bit uncertain now if the OCZ will be ok.
3) So the 800MHz RAM would not be operating at its optimum clock speed with a CPU that uses 1333MHz bus. Is that right?