Pros/cons of using 3 sticks of RAM on a dual channel motherboard

VeniVidiVidio

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Apr 7, 2014
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Hey all,

I've seen similar questions but this is a different spin... I just did a PC build for a combination of video and graphics work and gaming, and to make a long story short, I ended up with 3 sticks of DDR3-1600 4GB memory from two different manufacturers (1 Kingston HyperX Blu and 2 G.Skill Ares). I'm using an Asus Z87 mobo that supports dual-channel memory.

I know there can be issues mixing manufacturers because of different voltage and latency, but I considered looking up the specs on the RAM and trying it anyway since I'm anticipating a lot of video and image crunching with Adobe products.

My question is:
Is there actually any advantage to sticking 12 GB of memory (if it's compatible) in this motherboard? Or should I stick to running 8 GB just using the 2 sticks that match? My knee jerk response is "more = better" but based on what I've read about dual channel memory here, maybe that's not actually the case?

I just came back to PC from Mac, and it's been a while since I did DIY work on hardware, so I'm hoping someone with more experience/technical expertise can advise. Lurking here has been super helpful for understanding and picking components over the past couple months.
 
Solution
If the mobo supports flex mode it will run the two sticks in dual channel and the odd third stick in single channel mode, if it doesn't support flex mode then all 3 sticks will run in single channel mode, which will be a slight performance hit that you prob won't notice w/ 12 GB
I would personally never mix memory like that. However some of the newer motherboards are able to map the dual channel as dual channel and then the last DIMM is run in single channel. It might say in your motherboards manual.

Edit: sorry I had that wrong, if two DIMMs are used and one is larger than the other, it maps dual channel size to the smaller and the remainder on the larger DIMM is mapped to single channel use.
 

VeniVidiVidio

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Apr 7, 2014
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How about if they're all the same size?

Manual is unclear but I'm looking to see if it has more info I missed...I know the ideal configurations are 1, 2 or 4 cards of the same size, but since I have the extra RAM on hand, I'd install it if it was going to be useful.
 
I'm thinking that it will force all three to run single channel. If you have the RAM, just give it a try. Set the motherboard not to show the fancy POST screen, but the regular text screen. It should say what mode the RAM is running in on the POST screen. It may actually say in the BIOS itself, not sure.

However all that said, I wouldn't for two fold reasons:

1. It may cause weird issues like BSOD's or restarts.

2. If it does work, running in single channel mode will negatively impact system performance.
 

Tradesman1

Legenda in Aeternum
If the mobo supports flex mode it will run the two sticks in dual channel and the odd third stick in single channel mode, if it doesn't support flex mode then all 3 sticks will run in single channel mode, which will be a slight performance hit that you prob won't notice w/ 12 GB
 
Solution

wayneboyd1979

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Jun 21, 2018
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Isn't memory now controlled directly in the processor regardless of the main board.
Some cpus access memory in different ways not the main board today.
Your answers here will be always different to people's own set up or experiences