[SOLVED] Using only 3 RAM slots on a MOBO with 4 slots?

Nov 28, 2020
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Hi, I've got 16 gb of DDR4 ram at 3000mhz (2x8gb sticks) would be okay to add an extra 8 gb DDR4 stick in the third slot that is also 3000mhz (1x8gb) in a 4 slot motherboard and leave 1 slot empty? The extra stick has the exact same specs as the other 2 already in my build just a different brand (current 2 sticks are corsair, and extra stick is a gskill). My friend just had an extra stick laying around so I wanted to give it a try. I'm just wondering if there will be any repercussions using (3x8gb sticks) in a Motherboard with 4 ram slots?
 
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You will have problems. They won't be related to using 3 of 4 sockets but will be related to using different brands (corsair vs gskill). The fact that the specs are the same is irrelevant. At the very least your system will switch from dual channel mode to single channel mode.

Each module will use a 64 bit wide data bus. Dual channel mode makes the data bus look like it is 128 bits wide and will allow transferring data across that 128 bit wide bus. Single channel mode will make the data bus look like it is only 64 bits wide so your DRAM modules will only transfer half as much data.

If you want to expand your DRAM buy all new RAM in a "kit" that is guaranteed to work together, i.e. 2X16GB or 4X8GB. Otherwise you will have problems...
You will have problems. They won't be related to using 3 of 4 sockets but will be related to using different brands (corsair vs gskill). The fact that the specs are the same is irrelevant. At the very least your system will switch from dual channel mode to single channel mode.

Each module will use a 64 bit wide data bus. Dual channel mode makes the data bus look like it is 128 bits wide and will allow transferring data across that 128 bit wide bus. Single channel mode will make the data bus look like it is only 64 bits wide so your DRAM modules will only transfer half as much data.

If you want to expand your DRAM buy all new RAM in a "kit" that is guaranteed to work together, i.e. 2X16GB or 4X8GB. Otherwise you will have problems.

More info: https://www.tomshardware.com/reviews/ddr-dram-faq,4154.html
 
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