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Can I mix 16 GB and 32 GB RAM (DDR5) in a laptop?

Morgh

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Jan 10, 2025
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I know this wouldn't be an option with DDR4 as I would need to get a 2nd 16 GB, but with my currently factory installed 16 GB DDR5 it is already running in dual channel - so if I get another 32 GB, it should also be able to run dual channel - is it going to be fine?

(I *could* get another 16 GB of the same type that is installed but the max supported is 2x32 and I'll be probably using this machine for at least 5 years so I would get 32 now - working now either at 32 GB with a single stick or 48 if I can mix the new one and the old one and then buy another 32 in a few years... though maybe in a few years 2x32 will be much cheaper and there's no point in risking instability right now through mixing 16+32 and I should just go with 16+16 which should be more then enough for all my current needs?)
 
i don't know about laptops, i assume it's the same, but if it was a desktop i would say buy a perfectly identical stick, mixing them is always a bad idea.
 
If speed is different, both sticks will default to a safe JEDEC spec for DDR5. You can mix, it will run in dual channel up to the size of the smaller stick. If you do 16+32, you should get dual channel for 16gb and single for the rest 16GB.
 
If you mix them, it won't run in dual channel anymore. You'll have 32 GB (your 16 GB stick and another 16 GB from the 32 GB stick) in dual channel, and the remaining 16 GB in single channel. It works, but not the best idea.
 
Thank you - I guess I will just get a 16 GB then for now and will think about getting 2 x 32 when they are cheaper...
 
@Morgh
Depends:
-is the laptop equipped with 2 8GB Dimms?
-is the software "miss-reporting" dual channel because one ddr5 dimm can be reported as dual channel - internally 2x32bit, so , like in the old money one dimm would be 64 bit (single channel), 128bit( 2x64bit dual channel).

Followup: Aida64 , hwinfo64 may help elude without taking the lid off if you haven't done so already, there sure may be more software that can solve this mystery .
 
I will benefit from adding another 16 GB stick
You will. Undoubtedly. Try getting a stick as identical to yours as possible. Same batch would be perfect.
 
Whoa!!

Without knowing anything about the particular laptop (or motherboard or CPU), everyone here is just guessing - and sadly, not always offering correct information. :(

I know this wouldn't be an option with DDR4
That's not true. Again, it depends on the laptop (more specifically, the motherboard/chipset and CPU). And sadly, you told us nothing about this laptop, other than it runs 2 x 16GB of DDR5.

If you mix them, it won't run in dual channel anymore.
Again, it depends on the motherboard.

At this point in time, all we know is this laptop [apparently] has 2 RAM slots populated with 16GB sticks. It should be noted that some modern processors/chipsets/boards can support different size sticks in mixed modes with no problems. That is, access will run in dual channel up to the capacity of the lowest memory stick, then single-channel afterwards.

Some motherboards will not support dual channel unless the sticks are the same size. Same speed is no longer necessary with modern systems and I have to assume since it supports DDR5, it is modern. If different speeds, the speed of the slowest stick will be used.

That said, it is critical to note in almost every case, more RAM trumps faster RAM. So, if I was looking to improve performance by adding RAM, but did not have the budget for total RAM upgrade, I would not hesitate to run 48GB (1 x 16GB + 1 x 32GB) in single channel as that undoubtedly has the potential to offer significant performance gains over 32GB (2 x 16GB) in dual channel.

Do note that while dual-channel does improve performance, it does not come close to doubling performance as marketing hype often suggests. :(

should be more then enough for all my current needs?
I guess we are expected to be mind readers and already know your current needs. :( This leads me once again to point out that everyone thus far is just guessing. :(

So, we have no clue what your current or future needs are or will be. With that being said, depending on those needs (and your current hardware - which we know nothing about), it should be pointed out that 32GB is already a HUGE amount of RAM!

"IF" your current notebook has, for example dedicated graphics RAM for an integrated graphics solution, or better yet, a graphics card as some of the better notebooks do, AND if your notebook uses a SSD instead of a hard drive, it is very possible you will NOT "see" any performance gains by adding more RAM during your real-world use and therefore would just be wasting your money. That is why I said above, adding more RAM only "has the potential" to improve performance. It may not - except on paper (benchmark scores).

Also, if me, and I was set on upgrading my RAM, I would not do so until I built up my budget to fully upgrade and buy both sticks all at once. I would NOT buy 1 stick today, then hope to find and buy a matching stick later on down the road. You may be planning to purchase a 2nd stick in 2 or 3 months but life (and unexpected expenses) has a tendency get in the way of the best laid plans. If it ends up being 12 months instead of 2, a matching stick may not be available.
 
At this point in time, all we know is this laptop [apparently] has 2 RAM slots populated with 16GB sticks. It should be noted that some modern processors/chipsets/boards can support different size sticks in mixed modes with no problems. That is, access will run in dual channel up to the capacity of the lowest memory stick, then single-channel afterwards.

Some motherboards will not support dual channel unless the sticks are the same size. Same speed is no longer necessary with modern systems and I have to assume since it supports DDR5, it is modern. If different speeds, the speed of the slowest stick will be used.

That said, it is critical to note in almost every case, more RAM trumps faster RAM. So, if I was looking to improve performance by adding RAM, but did not have the budget for total RAM upgrade, I would not hesitate to run 48GB (1 x 16GB + 1 x 32GB) in single channel as that undoubtedly has the potential to offer significant performance gains over 32GB (2 x 16GB) in dual channel.

Do note that while dual-channel does improve performance, it does not come close to doubling performance as marketing hype often suggests. :(
Very true! :)

RAM speed doesn't improve system performance half as much as people like to say. Reviews usually argue about milliseconds, or 5% in minimum FPS, which is nothing. I have DDR5-6000, but I'm running it at 4800 for a reason. Lower SoC voltage which means less heat on my CPU, and really, there's absolutely zero difference. (Your mileage may vary)
 
Understood. I wasn't aware that specs of other hardware items is relevant. It's a brand new Lenovo Legion 5 with i5-13450HX, motherboard LENOVO LNVNB161216 (Intel HM770 (Raptor Lake-S PCH); RTX 4060 and 16 GB RAM 5600 in a single stick (and thus the second slot being free), 512 GB + 1 TB SSD drives.
Usually my RAM usage can get up to 95% and I did some hiccups here and there which would indicate more RAM would be beneficial.

I found the same product number Hynix 16 GB stick (HMCG78AGBSA092N) and thought about getting it as I've been told I'm risking a lot trying to match 1x16GB and 1x32GB
 
Understood. I wasn't aware that specs of other hardware items is relevant. It's a brand new Lenovo Legion 5 with i5-13450HX, motherboard LENOVO LNVNB161216 (Intel HM770 (Raptor Lake-S PCH); RTX 4060 and 16 GB RAM 5600 in a single stick (and thus the second slot being free), 512 GB + 1 TB SSD drives.
Usually my RAM usage can get up to 95% and I did some hiccups here and there which would indicate more RAM would be beneficial.

I found the same product number Hynix 16 GB stick (HMCG78AGBSA092N) and thought about getting it as I've been told I'm risking a lot trying to match 1x16GB and 1x32GB
It's a fairly new system, so I'd expect 16+32 GB RAM run in mixed channel (32 GB dual and 16 GB single) mode. As said above, not the end of the world. :)
 
You will give up dual-channel RAM.

It has been said to me that this is partial, that the first 16 GB of both DIMMs still run dual-channel, just not the last 17 GB on the 32 GB module. I don't know whether this is true or not. My testing was inconclusive.

Having said that, for most applications the slowdown will be barely or not noticeable. I run 2 laptops with mixed DIMMs.
 
I don't know whether this is true or not.
Well, if you read through the thread, you would have learned that it depends on the specific motherboard/chipset/CPU being used. Some motherboards support mixed modes, some do not. The OP needs to read his user manual to see what it says the board supports.
 
There is no motherboard manual to be found - the laptop "manual" does not include such things as channel support - only thing that was available on Lenovo sites for full specs was "Two DDR5 SO-DIMM slots, dual-channel capable". Furthermore the installed RAM stick is 5600 even though the motherboard/chipset/CPU/whatever clearly supports up to 4800...

I'm getting HMCG88AGBSA092N BA - 32 GB DDR 5600 stick (whose product number only slightly differs from the installed one - HMCG78AGBSA092N) and will test it out... if I run into instability, I have 14 days to return it for a refund, and if that happens, I'll just get a 16 GB stick
 
There is no motherboard manual to be found - the laptop "manual" does not include such things as channel support
:( I am not surprised. That is one of the problems with factory made computers in general, and laptops specifically.

I'm getting...
If not too late, try running the Crucial System Scanner on your system. This will help determine what RAM is compatible with your system. You don't have to buy Crucial RAM. This will report the specs of compatible RAM so you can choose a different brand, if you want. However, if you buy suggested RAM directly from Crucial, they will guarantee it will work. And last time I bought suggested RAM directly from Crucial, it was actually $10 cheaper than Amazon's price! :(
 
I know this wouldn't be an option with DDR4 as I would need to get a 2nd 16 GB, but with my currently factory installed 16 GB DDR5 it is already running in dual channel - so if I get another 32 GB, it should also be able to run dual channel - is it going to be fine?

(I *could* get another 16 GB of the same type that is installed but the max supported is 2x32 and I'll be probably using this machine for at least 5 years so I would get 32 now - working now either at 32 GB with a single stick or 48 if I can mix the new one and the old one and then buy another 32 in a few years... though maybe in a few years 2x32 will be much cheaper and there's no point in risking instability right now through mixing 16+32 and I should just go with 16+16 which should be more then enough for all my current needs?)
Is the factory RAM soldered in? That's often a problem with laptops. But if it's not, just buy a dual kit and junk or sell the stock stick.
 
Not soldered but I don't have the budget right now to get 32 X2. I could get 16x2 but seems just more logical to get a single 32 now and use with the 16 I have to upgrade to 2 X 32 in a year or two
 
I tend to look at the existing ram modules ics first on a laptop to know what will work then research it further to see what else might be. I refreshed a laptop from 2008 which had 3 gb and both modules were hynix, i found an off brand tgat used the same ics and 4 g made a big difference for windows 10

Good point.
Thats a huge problem today.
 
i don't know about laptops, i assume it's the same, but if it was a desktop i would say buy a perfectly identical stick, mixing them is always a bad idea.
I've used mixed RAM myself since the SDR era and I can count the problems I've had with single hand's fingers, and even that has been with modern(-ish) RAM kits with different XMP profiles and voltages. Maybe not recommended, but most definitely not a non-working solution.
 
Worst case scenario would be to sell the 16 and keep the 32 then add another 32 later although 64gb is probably quite overkill unless youre using the laptop in a professional setting or do a lot of video editing/3D rendering etc.

I have 32GB in my laptop and I have never seen usage close to 20gb (HP 830 G5)
 
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