12/24/48/whatever GB RAM sticks. Is there any catch?

[Macro Device]

Not so long ago, many manufacturers introduced DDR5 sticks of peculiar capacity. Is there literally anything I should pay attention to other than what I'd've paid attention to anyway, such as clocks, timings, $ per GB?

I assume the only stuff stopping me from outright using it might be an outdated BIOS version. Which is too easy to fix to even care about it.

I might be totally wrong. Am I?

More context: thinking about getting a B650 + Ryzen 9600X combo with a couple 24 GB sticks to call it "I'm prolly never gonna run out of RAM again."

 

[ShrimpBrime]

No catch. It's all about making more offerings for more sales. Mr. Crabs runs the show....

 

[TumbleGeorge]

12GB isn't exist in PC components. In this moment I see offer in one shop for kit of 2*48GB DDR5 5200(G.SKILL Ripjaws S5 and also Flare X5) which is little cheaper than 4*24GB. Not sure for the prices in Russia.

 

[Macro Device]

12GB isn't exist in PC components

SO-DIMMs do exist.

2*48GB DDR5 5200(G.SKILL Ripjaws S5 and also Flare X5) which is little cheaper than 4*24GB

I'm not doing 4x24, nor am I doing 2x48. I frankly don't even need more than sixteen. I just don't like upgrading very often so I'm planning on a double overkill RAM kit so it serves me well until it becomes Ivy Bridge obsolete.

 

[Shrek]

Not so long ago, many manufacturers introduced DDR5 sticks of peculiar capacity. Is there literally anything I should pay attention to other than what I'd've paid attention to anyway, such as clocks, timings, $ per GB?

Rank?

 

[Macro Device]

Rank?

Name's Shitposting. General Shitposting.

Jokes aside, the number of ranks doesn't really matter for what I'm doing (web browsing, movie watching, occasional photo editing, occasional gaming). I get single, I OC it harder. I get double, I just enjoy it. Whatever.

 

[TumbleGeorge]

SO-DIMMs do exist

There are lpddrx for mobile phones and tablets with this capacity(12GB). That's all. Where did you see so-dimm 12GB modules?

 

[Wirko]

I'm wondering if Intel's and AMD's memory controllers can handle weird combinations of sticks, such as 16+24+32+48 GB. Right now it's just curiosity but in a few years, when people start reusing their old components for new purposes, and try to use whatever is found in the drawers, good compatibility with mixed sets might have some practical value.

 

[TumbleGeorge]

I'm wondering if Intel's and AMD's memory controllers can handle weird combinations of sticks, such as 16+24+32+48 GB. Right now it's just curiosity but in a few years, when people start reusing their old components for new purposes, and try to use whatever is found in the drawers, good compatibility with mixed sets might have some practical value.

It has already been answered in other topics. But here it is in short. Yes, and this is not limited to computers. But when combining with different volumes and frequencies, the volume and frequency of the module with lower characteristics is automatically used. So, when combining 16+24GB, for the sake of simplicity and explanation with equal frequencies, 16+16GB will work in a dual-channel configuration, and 8GB (out of 24GB), which are more in one module, will work in single-channel. This is not 100% guaranteed!
Ps. Memory modules must be from one generation. DDR2+DDR3 or other combinations didn't work together even on motherboards which have slots for this two generations

 

[AusWolf]

I have 2x 24 GB in my Zen 4 system. It works just like 2x 16 would.

 

[efikkan]

Not so long ago, many manufacturers introduced DDR5 sticks of peculiar capacity. Is there literally anything I should pay attention to other than what I'd've paid attention to anyway, such as clocks, timings, $ per GB?

As long as the memory controller supports it (which it does), you should be all fine.
In cases where people want to mix different modules on a channel (not your case), it will work as long as the timings of the DIMMs are compatible, and if they're not they will usually fall back to a lower speed.

And in case you were wondering, these "odd" sized memory DIMMs are using larger memory chips, not more ranks of chips.

I'm wondering if Intel's and AMD's memory controllers can handle weird combinations of sticks, such as 16+24+32+48 GB. Right now it's just curiosity but in a few years, when people start reusing their old components for new purposes, and try to use whatever is found in the drawers, good compatibility with mixed sets might have some practical value.

They certainly can, it's very common in laptops to have e.g. 8 GB soldered, and an optional 8/12/16/24/32 GB SODIMM. (Just look at e.g. Thinkpads)

So, when combining 16+24GB, for the sake of simplicity and explanation with equal frequencies, 16+16GB will work in a dual-channel configuration, and 8GB (out of 24GB), which are more in one module, will work in single-channel. This is not 100% guaranteed!

The way it actually works is that the memory connected to a single channel is logically a separate memory pool, which is exposed to the CPU as a continous address space.

If a system is configured with mismatched capacities across channels (e.g. 16 GB + 24 GB), it's not like the last 8 GB will behave anything different than the first 16 GB of the second DIMM. If you add even load across the entire address space though, then it would appear as if the second DIMM is slower across the entire DIMM (not just a part of it), but it wouldn't behave like that in practice as the OS maps the memory in pages and applications don't access memory addresses physically.

There is also the question about ranks; dual rank modules, which is most of them, is logically two modules sharing a common bus, and will behave similarly to two single rank DIMMs. Mainstream platforms usually support 2x 2R modules per channel. There are some minor timing advantages to having just a single 1R module per channel relevant for OC, but for most practical uses having 2R modules are preferred as it usually achieves higher average throughput. With DDR5 timing is so sensitive that having more than 2R per channel is challenging for non-registered memory.

 

[Princess Garnet]

No catch.

The reason these sizes exist is because memory capacity used to be powers of 2, and capacity would increase by 100%, so they always remained powers of two, but scaling is getting harder for a lot of things, RAM included, so they settled on a 50% increase instead. 16 GB became 24 GB, and 32 GB (dual rank) became 48 GB. VRAM is about to do the same thing (2 GB to 3 GB)

This resulted in capacities that aren't powers of 2, so they seem abnormal, but there's otherwise nothing different about them. Many of us probably associate non-power of 2 memory capacities with mixed capacities, so we think there may be some tradeoffs, but other than the capacity itself not being a power of 2, which is arbitrary, nothing else is different.

In short, feel free to treat them like 16 GB and 32 GB DIMMs.

 

[AusWolf]

No catch.

The reason these sizes exist is because memory capacity used to be powers of 2, and capacity would increase by 100%, so they always remained powers of two, but scaling is getting harder for a lot of things, RAM included, so they settled on 50% increase instead.

This resulted in capacities that aren't powers of 2, so they seem abnormal, but there's otherwise nothing different about them. Many of us probably associate non-power of 2 memory capacities with mixed capacities, so we think there may be some tradeoffs, but other than the capacity itself not being a power of 2, which is arbitrary, nothing else is different.

In short, feel free to treat them like 16 GB and 32 GB DIMMs.

Yep.

There's a difference between running a 16 and a 32 GB stick for a 48 GB setup, and running two 24 GB sticks. The former will result in mixed channels, while the latter is a regular dual channel config like any other.

 

[Wirko]

The reason these sizes exist is because memory capacity used to be powers of 2, and capacity would increase by 100%, so they always remained powers of two, but scaling is getting harder for a lot of things, RAM included, so they settled on a 50% increase instead. 16 GB became 24 GB, and 32 GB (dual rank) became 48 GB. VRAM is about to do the same thing (2 GB to 3 GB)

Consumer DDR5 modules with 32-gigabit chips are coming "soon". Whenever that happens, the manufacturing cost per GB will probably be lower than in existing chips. This should drive at least one of the existing variants (16 and 24 Gbit) out of the market soon because it makes little sense for each of the manufacturers to keep making three different DDR5 dies.