A question about mixing RAM

[davout777]

Hi all,

I heard that mixing ram could be a issue.

I am wondering 'mixing ram' means mixing ram between my a1/b1 slot, or a1b1 and a2b2 slots?
I am having a good pair currently in a1 b1 and work well. Now I want to add rams in a2 b2, if I am using different brand/model, does this defined as mixing ram?? or mixing ram only mean mixing between a1 and b1, or a2 and b2?? ALSO, i am having 2x4g, can I add another 2x8g?? this cause any issue???

Thank you!!!

 

[hdmark]

Mixing ram usually means mixing any sticks bought from different packages. I think most people will say only ever buy in kits and use those sticks together. so even if you bought 2 kits of crucial 2x4gb 1600mhz ddr3 , they would say don't do it, you have to use a 4x4gb kit.

other people like me don't seem to have issues... I have 3 4gb sticks all purchased separately working 100% fine and have used int he past an 8gb stick with a 4gb stick again w.o issue

I think unless you are going for peak performance.... there should not be an issue with mixing different sticks of different capacities and even speeds. just know that all of the sticks will run at the speed of the slowest one.

so TLDR. mix and match all you want, its just not 100% garuanteed to work (although tons of us have never had an issue)

 

[davout777]

Mixing ram usually means mixing any sticks bought from different packages. I think most people will say only ever buy in kits and use those sticks together. so even if you bought 2 kits of crucial 2x4gb 1600mhz ddr3 , they would say don't do it, you have to use a 4x4gb kit.

other people like me don't seem to have issues... I have 3 4gb sticks all purchased separately working 100% fine and have used int he past an 8gb stick with a 4gb stick again w.o issue

I think unless you are going for peak performance.... there should not be an issue with mixing different sticks of different capacities and even speeds. just know that all of the sticks will run at the speed of the slowest one.

so TLDR. mix and match all you want, its just not 100% garuanteed to work (although tons of us have never had an issue)

thank you hdmark.
my current rams are bought in kit (2x4g). and I will buy another two in kit too. But do these two kits have to be the same model. if not, is this also counted as mixing???

 

[techgeek]

Mixing RAM means that all the RAM didn't come as a set. So in your case you originally bought a dual channel kit and now wish to add another dual channel kit.

Some people mistakenly assume that just because they purchased the exact same kit with the same part number for the second set, then they match. In some cases this is incorrect. Sometimes the manufacturer can't obtain the same RAM chips that they started a kit with, so they change them to something else. Everything about the DIMMs with the different RAM will look the same, like PCB, heatspreader, etc. However because the RAM is different it may have slightly different timings (not usually primary timings, but sometimes secondary timing, and tertiary timings) and may even have different voltage requirement.

The above situation is the best case scenario, your chances of both kits working together is pretty good. However mixing brands, and / or models is a much sketchier proposition. What is worse is in many cases it may appear to work fine most of the time. However you may experience very random problems that could be very infrequent in nature and be hard to narrow down to a mixed RAM issue.

I've mixed RAM and had it work. I've also mixed RAM and the system simply wouldn't POST. However for the least amount of headache, it's almost always better to replace the entire kit with a new larger kit rather than add to what you have.

Another thing to consider is the more DIMMs you have the greater demand that is placed on IMC. Depending the the CPU you have this could manifest different kinds of problems. If you are using high frequency RAM, and one kit worked fine at its non-JEDEC speeds, you may find that with two kits you are unable to use the faster profiles. If you overclock your CPU, you may find that your once stable settings are no longer stable with the addition of more DIMMs.

 

[Tradesman1]

Mixing RAM means that all the RAM didn't come as a set. So in your case you originally bought a dual channel kit and now wish to add another dual channel kit.

Some people mistakenly assume that just because they purchased the exact same kit with the same part number for the second set, then they match. In some cases this is incorrect. Sometimes the manufacturer can't obtain the same RAM chips that they started a kit with, so they change them to something else. Everything about the DIMMs with the different RAM will look the same, like PCB, heatspreader, etc. However because the RAM is different it may have slightly different timings (not usually primary timings, but sometimes secondary timing, and tertiary timings) and may even have different voltage requirement.

The above situation is the best case scenario, your chances of both kits working together is pretty good. However mixing brands, and / or models is a much sketchier proposition. What is worse is in many cases it may appear to work fine most of the time. However you may experience very random problems that could be very infrequent in nature and be hard to narrow down to a mixed RAM issue.

I've mixed RAM and had it work. I've also mixed RAM and the system simply wouldn't POST. However for the least amount of headache, it's almost always better to replace the entire kit with a new larger kit rather than add to what you have.

Another thing to consider is the more DIMMs you have the greater demand that is placed on IMC. Depending the the CPU you have this could manifest different kinds of problems. If you are using high frequency RAM, and one kit worked fine at its non-JEDEC speeds, you may find that with two kits you are unable to use the faster profiles. If you overclock your CPU, you may find that your once stable settings are no longer stable with the addition of more DIMMs.

__________________________

+1

This is addressed in my article (Fiction/Myths) items 1, 2, and 6, here:

http://www.tomshardware.com/reviews/ddr-dram-myths,4155.html#p7