Quick RAM Capacity Question

If a motherboard says it supports a maximum per DIMM capacity (in this case 8GB), is that a for sure indication a higher capacity stick will not work at all, or is it just that higher capacities didn’t exist when it was manufactured and they’re just covering their bases by only guaranteeing what they were able test at the time?

In this specific instance, I’m referring to an Asus M5A78L-M LX PLUS. It supports ECC memory and I have an 8350 lying around so I was going to make my new NAS with it.

The QVL/ limit is more of a promise that certain blessed things Will work with it at the nominated speeds they validated.
Often fast/larger ram modules will work.

Some systems Literally won’t work with certain configurations, so your mileage may vary.

Sometimes the Mobo manufacturer does not take full advantage of a chips capabilities, and some older boards had a memory controller on the motherboard.

Might be worth googling your cpu for ram addressability too, in case the total is restricted by cpu.

But if you already have the dims, it shouldn’t hurt to try a larger one.

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It completely depends on the type of motherboard and CPU. There are some were the limit is actually the limit, some were the limit can by bypassed, but with issues, and some were you can go over with no issues.

That board look like it has 2 DDR3 slots, and is AM3. Therefore, the max of 16gb is probably correct.

I have never seen a 16gb ddr3 unbuffered DIMM (ecc or non ecc), though they might exist? And I don’t think AM3 supports buffered ECC, so you are probably stuck with 2x 8gb modules.

The manual specifically says it supports unbuffered ECC and non-ECC RAM.

Not exactly sure what the difference is between buffered and unbuffered, or registered vs. unregistered for that matter.

But I found 16 GB DDR3 RDIMMs that say they’re for a Dell Poweredge, but RAM is RAM, amirite? (Probably not)

I haven’t bought the board yet, I’m just really bad at being resourceful and wanted to at least reuse something I have in my computer parts pile.

RDIMMS are registered. Those ones will NOT work in a system unless it specifically supports it.

My bad if I indicated otherwise

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Can confirm this will definitely cause issues in some cases, I have a bunch of registered DDR3-ECC that won’t work in my little NAS that uses DDR3-ECC non-registered :smiley:

AFAIK, registered = buffered? i.e. same thing different name.

I could be wrong, but that’s my understanding as is?

Yeah, I found a nearly identical board with 4 DIMM slots so I’ll just use a 4x8 Unregistered ECC RAM setup.

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Have you done a bit of Googling now to see why Registered memory modules can have higher capacity with their extra on board processing?
I don’t fully understand it beyond the basics, but it does seem super cool.
And I was surprised there was not non-ecc DDR3 Dimms over 8GB each, but there you go I guess.

I would say, if you wanted to maximise space, and if it was ECC you were interested in playing with, you might be able to pick up a used server with ECC ram, and CPU’s for a couple hundred bucks, but again, it would be spending money on an old platform, and newer stuff is more energy efficient, so small up from savings on initial cost might be drowned by running costs?

Oh yeah. One more tangentially related thing I was wondering about but couldn’t easily find a concise answer to online.

If you use ECC RAM in a board/chipset that doesn’t support ECC, will it not work at all or just work as non-ECC RAM?

Problem is with old server hardware is that especially if it is rack mount it is LOUD.

That imho is the bigger problem than running costs.

You can hear it from the other end of the house. Through closed doors etc.

Good point.

I don’t think it will work at all.
But I have not tried it…

I’m not sure my speculation is helping, and am gonna step back from confusing issues.

There was probably a reason why there was no cut and dry “yes” or “no” answer to be found. It could just be fundamentally different memory, or it could be regular memory with extra steps. I have no clue.

I am sure ecc is electrically compatible at a socket level.

I know ECC systems will run non ECC sticks.

I know one of my boards with nominal support for unbuffered ECC does not fully support the unregistered dims I have in them, but it does work with them in.
But I have not tried registered, because it is not supported on any of the boards I have.

the memory controller on is mostly on the cpu today.
If you look up the memory controller max supported volume you normally get a idea if denser DIMM volume will be supported in the future.
But not always , The example is the 920 940 etc supporting 48gb of ram where intel official spec is 24gb
Intel® Core™ i7-920 Processor (8M Cache, 2.66 GHz, 4.80 GT/s Intel® QPI) Product Specifications

And actually, many early x58 boards only supported 12gb of ram, but worked fine with 24gb+

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