I currently have 1 8GB stick of RAM in my computer that was purchased 2 years ago. I need to upgrade to 16GB - I’m regularly hitting over 85% usage.

I was told that even if I purchase the exact same brand, there’s a high likelihood that it won’t be the same. I also learned that pretty much all RAM is made by Samsung, SK Hynix, and Micron - and it’s really hard to find out which one is which.

Some folks recommended I purchase a good price/reputable brand and go with it. I did but after a new distro install, I’ve had many total OS lockup/freezes requiring a physical power button restart and I cannot be sure it isn’t the RAM. So I took it out today and am returning it.

So, moving forward, would you go ahead and buy two 8GB RAM sticks to ensure no issues? I kind of hate to do that as it feels wasteful to lose a working memory stick. Would you try a different brand? I could get a Samsung branded RAM stick, which I’m told likely won’t change over time. If it fails to be compatible, I suppose I could purchase a second and since it’s Samsung, it should be the same as the first. I also wondered about just getting a 16gb RAM stick, figuring it’s the same price as 2x/8GB and if it works with what I have, I now have 24gb usable RAM. If it doesn’t, I take out the old stick. But, of course, I lose any ability for the RAM to run dual channel for faster speeds doing that. I don’t know how much that really matters on a day to day basis. I’m not gaming on the computer. I use it mostly for a personal media home server.

Any suggestions/advice would really help. I’m quite “gun-shy” after having that first RAM purchase fail. I can’t be sure it’s the problem but I’ve not yet had a lock-up yet since taking it out either. Hard to say what that means. Thanks so much for any help.

System specs:
Intel NUC 8i7BEH
Core i7 8559u 4 core/8 thread processor
8GB RAM (currently), Corsair Vengeance (DDR4 2400mhz, CL17, 260pin SODIMM)
Intel Iris 655 Graphics
M.2 NVMe SSD (recent addition w/ the RAM that’s going back, is now my primary drive)
2.5” SATA SSD (still has Linux Mint on it from initial install 2 years ago)
USB 3.0 External HDDs

The RAM that’s going back in Patriot Viper Steel 2400mhz. It was rated very highly by pro reviewers and users. Intel said as long as the RAM size was the same (8gb/8gb, or 16gb/16gb) that it didn’t matter if the timings and other specs were identical and it would run in dual-channel mode. Still don’t know for sure if it was an issue for me at this point.

RAMs have a part number (see dmidecode --type 17) that may give you better information (I mean looking for the part number on the net).
Timing is an interesting issue, BIOS will try to find a common setup (which should work for all your RAMs), but sometimes it will mean a lower speed.
see: dual channel RAM wiki

But I'm sure that if you look at not only the brand but the complete ID as printed on the stick, you can find a suitable ( == identical ) pair.
I would do that.

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I thought when you do have two SIMMs or DIMMs that the MB and CPU would potentially split words or longwords across each of the sticks.

Could be badly wrong there, but I'd imagine that the operation of two concurrent RAM modules would be clocked from a common source and if they were different manufacturer, or different lots (also dates of manufacture) that they'd not work ideally.

I get it that you lament not being able to re-use the existing part you have, but I think you need to buy two identical parts for things to work consistently.

Without knowing anything about the 16GB DIMM its difficult to determine if that was the cause of your freezing.

Not a hardware expert but it does depend on motherboard capability and if the memory matches in size and DIMM configuration. If they do not match, memory stays in independent versus interleaved modes.
The motherboard does have interleaved support.

Your correct timing and speed does not matter. The system will be configured to the memory with the lowest speed.

Per the documentation
https://www.intel.com/content/dam/su...chProdSpec.pdf

Memory management is complicated and without context 85% usage does not mean much.

Always make sure you take appropriate caution when installing memory to avoid static discharge damage.

varaonaid,

I would be inclined buy a pair of matching, warrantied 8GB modules from Corsair, Crucial etc and then sell the current stick on ebay.

I remember buying extra RAM: the first time I failed much like you fear now, the 2nd time I was super cautious and read a PDF manual for both my mobo and the existing RAM stick before buying another one, and did not fail.
But the amount of limitations and things to consider was mind-boggling.

That's why I suggested that part number (= using the same type/part number should work), otherwise - as you wrote - hard to know the answer.

Eh, with modern Intel chipsets, it really is as easy as they say. As long as it is the correct type (DDR3, DDR4) and ECC type, it just works. With Ryzen, not quite so smooth (AMD hasn't gotten the integrated memory controller NEARLY as forgiving as Intels, although they've made strides), but Intels memory controller is quite robust and able to adapt. While it might not perform as well with mismatched SODIMM's as with matched, it will still work in dual channel, and as others have said, all ram will simply run at the speed and timings of the slowest stick as the ram controller isn't tied to the cpu clock, so it can run perfectly fine underclocked or overclocked.

^ OK, last time I did this I had an AMD CPU & mobo.

Obviously one wouldn't like the sticks to underperform.

No, but 16GB dual channel running slightly underclocked/under-timed is still > 8 GB running perfectly. Especially since overclocking RAM isn't possible on all but a VERY SMALL handful of laptops. But if you find some that shows the same DDR4 bandwidth/speed rating and shows the same timings (or at least very very very close), doesn't matter if it's different chips and such, they'll work fine at near optimum or optimum levels.

Totally agree with Tim. Unless you are running benchmarks, you will never notice the difference between perfectly matched and slightly underclocked ram.

Is this actual user usage, or cache/buffering? See https://www.linuxatemyram.com/ for more.

I ask with the following background (on my end): I have a few computers around here that only have 8GB of RAM as well, and none of them have issues doing what I consider 'basic' tasks (browsing the web, email, ssh, etc) and rarely go over 4-5GB actually 'used' (but will regularly be at 80-100% with caching). My big desk-side has 32GB and absolutely does see >8GB 'used' so I'm not saying its impossible, but that tower does other work too (like running VMs, compiling, and video encoding) which can chew up a lot of memory.

My point here is: if you're just seeing cache/buffer usage putting you at 8GB, I wouldn't bother too much with an upgrade - you'll just see even more cache/buffer usage. But if you're actually needing >8GB for applications, read on...


While true, this pretty much doesn't matter unless you're an overclocker.

It is not uncommon (but also not 'standard practice' that I've seen) for a RAM seller (lets say Kingston for example) to have a part number for some DIMM (say a 8GB DDR4-2400 DIMM) and change suppliers for the actual DRAM dies at some point in that model's production, but usually manufacturers are good about throwing a revision number or some other signifier into the product name. Worrying about the provenance of the specific DRAM devices, again, does not matter unless you're looking to overclock, because with modern memory you can generally trust that it will run at its advertised (JEDEC) clocks. The bad old days of the 1980s-1990s are long behind us.

It's impossible to say waht caused your problems, what your problems were, etc - this is a common troubleshooting fallacy though, where 'the last thing that was touched' takes the blame for every problem the machine ever has. Without concrete information or troubleshooting the issue, nothing more can be authoritatively said here.

The goal here being to have 16GB in dual channel? Given current memory prices this is probably the easiest way to go, so yeah, I'd go ahead with that plan. 'Reputable brand' is a little nebulous these days - even the 'no-name' stuff is not likely to be really anything awful, it just won't have slick graphics/stickers/etc associated with it, and probably doesn't have the best timings/clock relationship. If you stick to 'name brands' (e.g. Corsair, Kingston/HyperX, Crucial/Micron, G.Skill, ADATA/XPG, Mushkin, Patriot, PNY, OWC, etc) there should be absolutely no problems, and you should expect the warranty to be for real. If you don't mind buying 'used' parts, it's usually possible to find HP or Dell-branded memory on ebay for relatively cheap, and most of that is usually OEM Samsung or Hynix (as in, Samsung or Hynix are actually making the whole module, not just the DRAM), and decent quality too, but no warranty (since its used).

Yeah, upgrades can be like that.

From what to what?

Told by who? It feels like there's more people in this conversation than are represented here - so who else am I/are we talking to? I don't mean this in an adversarial way, I just want to be clear on communication.

Compatible with what? If it's the right type/form factor for your current system then its compatible - stability with the other module is another question (which I know I'll get to before the end of this reply).


This, I would probably not do. You will likely lose dual-channel configuration here, which will cut memory performance down (keep in mind: you don't have dual channel currently, so you won't 'lose' anything that you already have). If this machine only takes two DIMMs and you need maximum capacity on the cheap, however, this would be the way to go (vs buying a 32GB kit).

'Does dual channel help?' is something that's been debated since it first came out, and the results are usually pretty mixed - it isn't just about gaming though, I can tell you that (basically anything that depends on memory performance will be impacted). Currently you don't have dual channel (with only one module you cannot), so going from single -> single won't change anything, basically you're weighing just a capacity upgrade vs a capacity + performance upgrade. If the system uses an IGP, the dual-channel memory switch will be a 'bigger deal' because the graphics depend on the system memory too.

Again, without really troubleshooting the issue it's impossible to say authoritatively what went wrong. My guess, however, is that you had timings setup wrong between the two modules for stability.

Intel is right, but with a lot of 'terms and conditions may apply' kind of qualifiers.

Where they're right:
- If the memory modules are the same size they will run in dual channel if the BIOS acknowledges it.

Where they are in a grey area:
- That it will automagically work just fine.

What the system is supposed to do is try to find a common timing/clockrate between two modules, if the modules are the same then they obviously find a common configuration, but if they're different (e.g. two different products, as you have here) it may or may not find a good common ground. Usually this 'works out' but sometimes it does not, and may lead to stability problems - the general guidance is to try relaxing the timings or choosing a less aggressive clock in that scenario. So for example if DIMM #1 is 9-9-9-24 DDR3-1333, and DIMM #2 is 10-10-10-30 DDR3-1600, you may need to run at something like 10-10-10-30 DDR3-1333 even though its 'sub-optimal' for at least one module. This does require trial and error to 'get right' when using mismatched modules, but doesn't mean you cannot use mis-matched modules.

It also possible that other things went wrong with the system:
- The new memory you bought is actually, genuinely defective.
- There is some other unknown configuration error with the system.
- Something else is faulty and is being noticed because the machine is being scrutinized following an upgrade.


To the original question, if you actually need >8GB for user applications, and want the best possible performance, I would agree with getting a 2x8GB (or 2x16GB) kit and going from there - yes it means having a DIMM sitting in a drawer but that's just the nature of upgrades. If you have some other machine that could use 8GB of memory, it could be a good candidate for a hand-me-down. If that's not possible due to price, I'd first look at used prices, and then give another 8GB DIMM a shot, assuming you can actually adjust memory timings in the system's BIOS (I don't have much experience with the NUCs though - if they're entirely locked out, that's probably a non-starter).

Dual-channel operation works if the chipset/memory controller supports it, and its enabled properly in BIOS (some older AMD K10 machines seem to not automatically engage this, even with matched DIMMs and everything properly plugged up - I don't know why), and yes the memory will try to find a common clock/timings, but when left to do things on 'Auto' it may not pick sane defaults if it cannot find a common JEDEC profile between the two devices.

For 'out of the box' consistency, yes buying a matched pair is ideal. That said, the bad old days are fortunately long behind us, and I've yet to see a system with mis-matched DIMMS that cannot be made to work with at least some hand-holding (assuming the BIOS permits such changes - a lot of OEM machines lock everything out, and may even lock you into using their branded memory upgrades if you want to keep your warranty/whatever, which is one of many reasons to avoid pure OEM machines).

Interleaving. It's been around for a long time. If memory serves my Micronics '486 motherboard (first system I ran Linux on) would use 4-way interleaving if you installed identical memory boards on it.

Agree about the matched memory boards. Even that's no guarantee, though. I once purchased (mail order) what I was told were matching memory boards and the system complained big time when it was under stress. I'd boot the system into MemTest86 and run through the complete memory test suite. If it passes, the system should run Linux without a hitch.

I have a few old memory parts laying around from doing exactly what the OP is hesitating to do. They might make geeky key fobs.

Cheers...

85% usage of RAM or CPU? Also why is that bad?
Is your machine over-heating? Is there stuttering on the graphics? Or the fan noise is too loud?

If your machine is working fine at 85% RAM usage - then that is because your RAM is supposed to operate normally at that level.
If the RAM usage goes beyond 100% - then an upgrade is necessary.

That doesn't really make sense, does it?
Simply buy another 8GB stick with the same spec - and you're good to go.
RAM should also be run in dual channel anyway because the machine performs better that way.
So I agree disposing of your 2-year old 8GB stick is a waste. Simply buy another same spec 8GB stick with the same brand name.

Also Infineon and Elpida (now defunct). Yes, only a few companies make RAM for the whole world - so naturally they got into price-fixing.
This ended when Elpida lost its nerve and sang like a canary.

I bought cheap Chinese-brand RAM and yes, I looked at the photos carefully and could see they were Japanese Elpida RAM.
I haven't looked recently to see if Elpida RAM is still available.

But RAM is not about brand name - it's about specification.
We hear about HDD dying but not about RAM dying.
So I suggest you get another 8GB RAM stick with the same brand name and specs so its compatible with your machine.

If you have a new linux install you will inevitably encounter teething problems.
It is not necessarily anything to do with your RAM.

Please don't use an 8GB RAM stick with a 16GB stick in dual channel.