Dual channel memory with different RAM size

[ayushj]

Hey

I'm looking to increase the amount of RAM in my laptop. I currently have 1 4GB DDR4 stick and I'm trying to choose between another 4GB ram or an 8GB one. The memory speed/latency/voltage will be same but it'll be a different brand.

I've heard (and read previous threads) that you need to use the same RAM size for dual channel but in my laptop's manual (see spoiler below), they say you can Dual channel with 8192+4096 MB ram for a total 12GB RAM, but later it's mentioned that you need the same size. I'd really like to get the 8GB ram if I can dual channel with it.

Spoiler

MEMORY
- DDR4 PC4-2133
- Supports Dual Channel Memory

Standard
- 2048 MB Total System Memory (2048 MB x 1)
- 4096 MB Total System Memory (4096 MB x 1)
- 6144 MB Total System Memory (4096 MB + 2048 MB) (Dual Channel)
- 8192 MB Total System Memory (4096 MB x 2) (Dual Channel)
- 8192 MB Total System Memory (8192 MB x 1)
- 12288 MB Total System Memory (8192 MB + 4096 MB) (Dual Channel)
- 16384 MB Total System Memory (8192 MB x 2) (Dual Channel)

Technical Specifications
Dual-channel
- Maximized dual-channel performance requires SODIMMs of the same size and speed in both memory slots.

 

[Tradesman1]

If whatever you get with play with the old you will indeed have 12GB total - it will be running in flex mode, with 4GB from each channel running dual channel mode and the odd 4GB in single channel mode 😉

 

[ayushj]

If whatever you get with play with the old you will indeed have 12GB total - it will be running in flex mode, with 4GB from each channel running dual channel mode and the odd 4GB in single channel mode 😉

Thanks, that's good to know. Buy why does it later say that it "requires SODIMMs of the same size .." for maximized performance? Can I safely ignore that bit?

 

[Tradesman1]

Should have Flex mode built in, especially running 2133 DRAM, so should be fine, might be a little CYA on their part if people mix and have problems, or they haven't put much time into the BIOS

 

[ayushj]

Should have Flex mode built in, especially running 2133 DRAM, so should be fine, might be a little CYA on their part if people mix and have problems, or they haven't put much time into the BIOS

Thanks for the help . I'll go ahead and try it.

Could you help me pick one from these options?
Corsair ValueSelect
Kingston ValueRAM
Kingston HyperX
G. Skill Ripjaws

The G-Skill one has "automatic overclocking" feature but I'm not sure if that'll play well with my normal Hynix RAM. The Kingston HyperX has automatical overclocking as well as a lower latency timing than my current RAM (13-13-13 vs 15-15-15-36). Looks good but again, I'm looking for compatibility.

Let me know if I should start a new thread for this.

 

[Tradesman1]

Think I'd try the GSkill, it will be a stronger stick and might well be easier for it to play with another different stick

 

[ayushj]

Thanks, went with the G.Skill.

Would it matter performance wise that the extra 4GB will be running in single-channel mode?

 

[Tradesman1]

Not that you'll notice 😉