Basic RAM questions from a noob.

[Gorganoth]

I skimmed through the Memory FAQ document, but couldn't find clear answers to these basic questions.

I apologize in advance that I'm not familiar with the terminology.

So i recently bought a motherboard (MSI Z270-A Pro), that has 4 ram slots, do I need to use all 4?

If I have a ram 'kit' that comes with 2 ram cards, can I just buy the same kit twice and have double the ram? Can I mix and match and use ram cards from different kits / manufacturers, or would that not work?

If I don't use all the ram slots, is it irrelevant which slots I use?

Thanks in advance.

 

[Rexper]

"that has 4 ram slots, do I need to use all 4?"

No.

"If I have a ram 'kit' that comes with 2 ram cards, can I just buy the same kit twice and have double the ram? Can I mix and match and use ram cards from different kits / manufacturers, or would that not work?"

Maybe, maybe not. There will always be a chance two kits of ram are incompatible with each other. This is why manufactures put in the effort to find a compatible pair and label them as a 'pair' and market them at a higher price. As the specifications of the two kits become more similar, the probability of a compatible kit increases, though will never reach 100%.

"If I don't use all the ram slots, is it irrelevant which slots I use?"

It is not irrelevant, as using a pair of sticks of ram in specific slots of the motherboard will enable Dual Channel Technology to be utilised (these slots can be determined through the motherboard's manual). Otherwise, they will work as Single Channel.

Alot of RAM related questions, including these, can be found in this large post created by 526Christian at PcPartPicker: Main Memory: A Primer

[Quotes italicised & line-spaced to isolate them from replies - - Moderator]

 

[exroofer]

Mixing Ram from different kits "may" work, if they are the same specs. I have two different kits installed, but they are otherwise identical.
In general, mixing ram is a bad idea. Your mother board manual will tell you which slots to use with 2 sticks.

Read
The
F******
Manual


Lol.

Usually when using 2 of 4 slots, you use 1 and 3 slots. or 2 and 4 slots.
They are often colour coded as well. Again, motherboard manual.

Ram "kits" are pairs of sticks that the manufacturer has tested and will garantee to run at the advertised speeds when used with the appropriate cpu and mobo.

Most modern systems are "dual channel" memory, thus the pair of sticks. This means that one can be written to alongside the other one being read. When the system boots, it will look for ram in the slots it expects ram to be.
If it is in the wrong slots, only one stick may be recognised, or the system may not boot.
If this happens, don't freak out. Again, manual.

If you need specific advice about which ram to get for a build, please post more info.

 

[MeanMachine41]

Hi Gorganoth

You do not need to use all RAM slots. Just one slot can be used however your RAM will be in single channel mode. 2 slots occupied in the correct slots will give you dual channel mode.
Slots are usually listed as DIMMA1, DIMMB1 ,DIMMA2, DIMMB2. To use a two slot config you would use DIMMA2 and DIMMB2 like in pic below.

Buying the same kit twice can be problematic even with both kits being the same spec. DO NOT get kits from differing manufacturers as you will have problems.
Very often two similar kits will work together however slight variations in Latency can cause issues and would involve Bios changes to Timings and voltage which can be a frustrating exercise. It is always best to get a single kit the size and frequency you desire.

 

[InvalidError]

Mixing Ram from different kits "may" work, if they are the same specs.

Mixing RAM can work regardless of specs but the BIOS should default to the slowest specs of the bunch. Having same-spec'd RAM merely reduces the likelihood that the configuration won't work. If you are unlucky, it is entirely possible to still have compatibility issues with a "matched kit" due to variations in the CPU, motherboard and DIMM/DRAM manufacturing process. Build 10 identical systems and you may have one that doesn't work until you swap the RAM with one of the others.