"Single Channeled" RAM stick for "Double Channel" slot?

[George Jill]

Hi,
I am a newbie to this forum and have had a question over RAM compatibility, hopefully someone will help me to this issue.
I am planning to buy a laptop with model HP-15-ay030tu which has its stock DDR4-2133Mhz 4GB RAM stick with dual channel option. I want to add another DDR4-2133Mhz 4GB RAM stick to its remaining slot and I'm preferring to have G Skill Ripjaws 4GB DDR4-2144Mhz F4-2133C15S-4GRS RAM stick for this purpose. But RAM stick with the mentioned model number is said to be "Single-Channel" from its manufacturer's website (Click Here). Now I've fallen into a confusion whether I should install that so told "Single Channeled" G Skill RAM stick to the laptop's "Dual channel" slot or move to another RAM stick with different brand+model.
Will it be safe and hassle-free to install that G Skill RAM stick if I interimly suppose both the stock and additional RAM sticks have same timings parameters?

Thanks in advance for any help.

 

[Karadjgne]

Apples and oranges. Both fruit.

The single channel ram you have is single channel only because it's in 1 slot. There is no single channel slot and dual channel slot, both are single channel. So matters not which slot the single stick is in. It's only when both slots are populated that the ram will run in dual channel mode. Channel A is single, Channel B is single. Channels A+B = dual.

That said, there are no guarantees when mixing ram. Everything from vendor to model, size, speed, timings can be identical and they can still not play well together without voltage or timing or speed adjustment. Or they may work great. Or not at all.

Only a full new kit of 2 sticks in the same package is tested by the factory to be fully compatible, all else is pot luck. They may work, they may not. No one can tell.

 

[George Jill]

Apples and oranges. Both fruit.

The single channel ram you have is single channel only because it's in 1 slot. There is no single channel slot and dual channel slot, both are single channel. So matters not which slot the single stick is in. It's only when both slots are populated that the ram will run in dual channel mode. Channel A is single, Channel B is single. Channels A+B = dual.

That said, there are no guarantees when mixing ram. Everything from vendor to model, size, speed, timings can be identical and they can still not play well together without voltage or timing or speed adjustment. Or they may work great. Or not at all.

Only a full new kit of 2 sticks in the same package is tested by the factory to be fully compatible, all else is pot luck. They may work, they may not. No one can tell.

Thanks a lot for the reply. So, it feels like that G Skill's "Single Channel" annotation is something very common for general usage of additional RAM sticks and synchronizing two RAM sticks in two channel slots isn't that trivially easy task without the case of same package modules for both stock and additional slots.

 

[Karadjgne]

You are skipping all around reality. All ram is single channel. At least. The channel itself is the motherboard, not the ram. So 1 stick of ram in 1 slot will run single channel. Almost all ram is also dual channel capable, there are tri and also quad channel capable ram. There are tri and quad channel mobo's. A standard mobo with 4 slots has 2 channels. Channel A and channel B. On the board. They look like AABB, starting at the cpu socket. So slot 1 is channel A, as is slot 2. If you populate 1 and 2 you get ram that's all working in single channel, Channel A. Same if you put both sticks in 3-4. If you put ram in 1-3 or 2-4 then you use channel A+B, dual channel.

That's a standard ATX motherboard layout. If you have a laptop, notebook, M-itx or some mATX motherboard that only has 2 ram slots, you get AB, not AABB. So 1 stick in either A or B runs single channel, if you use both slots, A+B, you use dual channel. Dual channel runs @10% better performance, so it's advisable to have 2x 4Gb sticks vrs 1x 8Gb stick etc. Size maybe the same, but the memory controller in the cpu is optimized for using 2 channels vrs 1.

Ram itself is made from Silicon. Silicon is not entirely pure, you will get trace elements in it. These trace elements will affect exactly how ram responds to the voltages and timings. Using a kit, the ram is coming from the same chunk of silicon so the ram sticks all respond the same, even under secondary or tertiary timings. Using different kits, you run the chances of having silicon that just doesn't respond the same, so you get irregularities.
If, say, you have kit-x which has mostly nickel trace and kit-y with mostly copper trace, they may work well together as the properties of the traces are similar enough that they really don't affect the secondary and tertiary timings. But if kit-y had carbon traces, there may be such a difference that the ram simply will not work no matter how much voltage you try and cram in there. With such a huge amount of possible different trace amounts and varieties, you'll get repeats overlaps compatability etc but you'll also get incompatible ram or ram that just needs a little bump in voltage to work right. It's all pot-luck guess. You can have identical ram from 2 different packages that simply will not work, or very different ram that will. No telling. Only ram packaged together in a kit will have a guarantee to work. Not only are they tested at the factory as compatible, but they also come from the same batch of silicon.

So if you want guaranteed 2x sticks of ram with no incompatibility, you buy a kit of 2 sticks. If you want to take your chances on an upgrade, you buy 1 stick and hope it works with your existing stick. It might, it might need tinkering, it might not. No one can possibly tell by looks or speeds or brand or timings.

 

[scuzzycard]

Hi,
I am a newbie to this forum and have had a question over RAM compatibility, hopefully someone will help me to this issue.
I am planning to buy a laptop with model HP-15-ay030tu which has its stock DDR4-2133Mhz 4GB RAM stick with dual channel option. I want to add another DDR4-2133Mhz 4GB RAM stick to its remaining slot and I'm preferring to have G Skill Ripjaws 4GB DDR4-2144Mhz F4-2133C15S-4GRS RAM stick for this purpose. But RAM stick with the mentioned model number is said to be "Single-Channel" from its manufacturer's website (Click Here). Now I've fallen into a confusion whether I should install that so told "Single Channeled" G Skill RAM stick to the laptop's "Dual channel" slot or move to another RAM stick with different brand+model.
Will it be safe and hassle-free to install that G Skill RAM stick if I interimly suppose both the stock and additional RAM sticks have same timings parameters?

Thanks in advance for any help.

Might work, might not. The only way to guarantee stable dual-channel operation would be to yank out the memory that's already installed and to install a dual-channel kit consisting of 2 matched modules.

Mixing memory has been sketchy since the 1980s, but only recently has it become so sketchy that it hardly ever works due to increasing speed.

 

[Tradesman1]

Real short - a stick of DRAM is a single 64 bit device...period. When two are configured in a 'dual channel' mode the MC (memory controller) sees both sticks as a single 128bit device. (if supported 3 sticks are 'seen'/'used' as a single 192 bit device if tri channel is supported and for quad channel the 4 64bit sticks are 'seen' as a 256 bit device 😉