Does "DIMM" necessarily refer to unbuffered ones? Is it possible to support buffered/registered ones?

[Matthew Wai]

http://download.gigabyte.us/FileList/Manual/mb_manual_ga-h81m-ds2_v3.0_e.pdf
My GA-H81M-DS2 works fine with 2 x DDR3 Unbuffered DIMM.
In the above manual, on page 7, it says "DDR3 DIMM sockets". Does "DIMM" necessarily refer to unbuffered ones? Is it possible for the motherboard to support buffered/fully-buffered/registered ones?

 

[asoroka]

Your mother board only supports standard DDR3 unregistered non-ECC consumer RAM.

For what its worth. DIMM stands for Dual Inline Memory Module. Its a double SIMM (Single Inline Memory Module)

 

[Matthew Wai]

Your mother board only supports standard DDR3 unregistered non-ECC consumer RAM.

So, was the manual writer negligent in not mentioning that? How can one find such omitted important information when assembling a PC?

 

[Peter Martin]

it's called google

manual writers cannot include everything that you should already know. do your research

another way to learn is experience

 

[Matthew Wai]

https://ark.intel.com/products/75016/Intel-H81-Chipset
It says nothing about "unbuffered", "unregistered", "non-ECC" etc.

 

[Matthew Wai]

https://www.pcworldbusiness.co.uk/catalogue/item/OCZ+DDR3+PC-10666+-+1333MHZ+GOLD+2GB+MODULE/P111821P

I am using the above RAM. The webpage says "1.65 V", but my Piriform Speccy says "1.500 V".
Why is there discrepancy?

 

[asoroka]

The default is non-ECC, unbuffered. The other stuff is more expensive. So unless your motherboard explicitly says you need it, you dont.
It would only be a professional workstation or server that would use that kind of memory.

Consumer grade boards will just use standard unbuffered(unregistered) non-ECC RAM.

Most memory runs at 1.5V. The exceptions are Low power (1.35V). and some high performance memory which can run as high as 1.65.

Your motherboard is probably defaulting to 1.5V. There is probably no reason for you to change this value.

You RAM can use higher voltage, but does not need it.

Is there anything else we can help you with?

 

[Matthew Wai]

Your motherboard is probably defaulting to 1.5V. There is probably no reason for you to change this value.

Right. I just found that the default in BIOS is 1.5V, and there is no way for me to change this value.

You RAM can use higher voltage, but does not need it.

Then what is the purpose of marking its voltage as 1.65V? Is it always okay to buy 1.65V RAM when a manual says the sockets are for 1.5V as my manual does?

 

[asoroka]

The voltage on your RAM is the maximum that can be applied. It also works at 1.5V, but you probably can't overclock.

You don't have to buy 1.65V ram, you can buy 1.5V Ram if you wish (slower and probably cheaper).
eg Kingston KVR16E11K4


Are we solving a real problem here?

 

[Phillip Corcoran]

it's called google

manual writers cannot include everything that you should already know. do your research

another way to learn is experience

Excellent comment.

 

[Matthew Wai]

Are we solving a real problem here?

I don't have a problem with my RAM at the moment. I just want to know which RAM I should buy if need be, as there is no guarantee that my RAM will not fail. I bought the second-hand 1.65V RAM because it was cheap.

Another question: is it correct to say that two RAM sticks of different sizes and speeds can be used together as long as they have the same CAS latency?

 

[asoroka]

You will get best results if they are the same.

As long as you use settings for the lowest ram, it will be fine.

If you have different sizes then it starts to get complicated, try to keep RAM in each channel the same size (you normally have 4 slots and 2 channels).
So try to buy them in pairs otherwise you will not use all teh RAM you paid for.

 

[Matthew Wai]

You will get best results if they are the same.

If they are not the same, I will not get best results, but they can still be used together.
Am I right?

 

[asoroka]

yes but if you mix a 4GB plus a 2GB on the same channel, you will only have 4GB total memory. (The 4GB will only show 2 GB to remain compatible with the other chip).

 

[Matthew Wai]

yes but if you mix a 4GB plus a 2GB on the same channel, you will only have 4GB total memory. (The 4GB will only show 2 GB to remain compatible with the other chip).

I think they are not on the same channel because the manual says "The two DDR3 memory sockets are divided into two channels and each channel has one memory socket".
So, should the total be 4 + 2 = 6GB, in which 2 x 2GB operate in dual channel mode and the remaining 2GB operates in single channel mode?

In the following case, 4GB RAM and 8GB RAM were used together, and the total usable memory was 12GB. Am I right?
http://www.tomshardware.com/answers/id-2595225/mixing-sized-rams.html

In the following thread, geofelt said "With a 4 and a 8 gb stick,(on an intel processor) the first 4gb will operate in dual channel mode, and the odd 4gb will be in single channel mode.", which meant that the total usable memory was 12GB. Am I right?
http://www.tomshardware.com/answers/id-3611007/mixing-amounts-ram.html

 

[asoroka]

Sorry my mistake.

In dual channel mode (which you have) the modules must be the same size (or it will use the size of the smallest).

So on your motherboard 4+8 will be 8.

If you can disable dual channel mode then you will get 8+4=12. I am not sure about your BIOS.

I am not sure that I can help you much more.
The advantage over just one stick will be speed, but you won't get 12 GB

 

[Matthew Wai]

https://lifehacker.com/5598716/what-are-the-rules-on-mixing-two-different-types-of-ram
The above article says "make sure each stick has the same CAS latency, timings, and voltage.[/color]"
I use two different sticks. OCZ: CL 9-9-9-20 1.65V and Unifosa: CL 9-9-9-24 1.5V.
I know my BIOS has automatically changed 1.65V to 1.5V (default), so the same voltage is used.
But how about the timing? Their tRAS values are different. Why can they work together?
The timing values are shown on Piriform Speccy.