Just How Bad is Mixing Memory?

[James]

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See what happens when you mix RAM DIMMS from different manufacturers!

 

 

 

[SignatureSigner]

Your going to have a bad time... Just a guess.

Want to make it worse? Diff timing and supported speed. This will be fun.

[Quackers101]

Can I put my GPU memory in the memory slot?

[Sakkura]

If you mix memory, your face will end up looking like James' avatar.

[samcool55]

My single 2400Mhz CL16 ram stick is running fine with my 3600Mhz CL19 sticks (2 of them).

It does only run at 3200Mhz and CL20 which isn't perfect, but can't complain about that 2400Mhz stick!

 

I basically loaded the DOCP of the 3600Mhz stick, turned it down to 3200Mhz and 0 issues so far...

[James r.]

I'm still running ddr3 from three different manufacturers. Would my rig eventually have similar issues as the one in the video

[PlayerLorenzo]

BSODs all over the place. 

[James r.]

1 minute ago, PlayerLorenzo said:

BSODs all over the place. 

lmao you'd think so right

[Quackers101]

a sea of blue screens, just don't make it salty.

[sub68]

laughs with 3x2gb and 1x8gb ram config that works great

[Nystemy]

My prior rig started out with 2x16 GB memory, and then added another 2x16 GB of memory with wildly different specs (actually better specs) some time later... (all on DDR3)

The thing I did were to place the two old modules in one channel and the other modules in the other channel. Since I have had experience before where mixing stuff on the same channel leads to issues.

 

The video could though have been stretched out a fair bit to be honest and gone into a bit deeper level of different setups.

Since there weren't really any clear information of what exact setups were even tested to be fair. (Other than the unbalanced amount of memory per channel and the somewhat unrealistic 4 modules from all different manufacturers.)

 

In short, I am curious to what happens if we configure our setup with modules from two manufacturers, that either are on separate channels, or mixed on the two channels. What is the difference in system stability?

Also somewhat curious about mixing non-ECC modules with ECC ones on a platform that supports ECC memory. Does it fall back to non-ECC mode or does it run ECC on the modules that support it? (Obviously is can't run ECC on the modules without ECC support.) Or does it just not boot due to the mix? _{(A good system would ideally be able to differentiate between the two and run "critical" stuff on the ECC modules, and "who cares if it glitches" stuff on the non-ECC modules. But I guess this is just as much of a can of worms to implement on an OS level as NUMA is.)}

 

Then I am also curious.
How independent are the memory channels from each other on different platforms? (Ie, AMD Ryzen, AMD Epyc, Intel core, Intel Xeon.)
Ie, can one run a channel at a higher frequency than the other ones, and with different timings as well?

I haven't dabbled too much with memory overclocking myself, but I don't recall any settings for the individual channels being a thing. _{(Though, I wouldn't be surprised if all the channels are interleaved across the address space and not used as separate blocks one after the other. Since interleaving would give better performance for applications running with very little memory, ie mostly single threads. Using the memory as blocks one after the other could though have certain advantages to applications that are more careful in how they manage their own memory resources, not to mention have potential of increasing system responsiveness since the memory bandwidth becomes more segregated between applications so that they don't need to wait on each other in the same fashion. In short mostly applicable in the server sphere...)}

 

We could also throw in a wrench and look at persistent memory dimms used as memory, but I feel that is a different topic... (Ie stuffing in an Optane module on the same channel as RAM module.)

[Razor512]

Mixed can work but it takes a bit of planning and testing.

 

For example, mixing a 3200 kit with a 3400 kit both being CL16-16-16-36.

 

The first test is to see with the old slower sticks, is how far can you overclock while on the XMP timings, and also testing which voltages the DRAM dies can safely handle.

 

For example, if you have 2 3200 and 2 3400 modules but at 1.42V both sets are able to hit DDR4 3600 speeds, then you can mix and match while also getting a small overclock out of them.

 

In cases of a large bin difference, you will be doing a mixture of an overclock and underclock, where you may find some middle ground between the fastest and slowest sticks. Beyond that once everything is initially stable, then do your prolonged memtest.

[WhitetailAni]

<glances at Minecraft server running 2 2GB DDR3-1333 sticks and 2 4GB DDR3-1600 sticks running at DDR3-1366 CL9, with the Phenom II X4running at 4.1 GHz 2 cores disabled, running Cinebench R23 multi-core with CPU temps at 45 C>
<remembers that he had it running at 1400 MHz 2 weeks ago>

<smiles>

[2DPrinter]

1 hour ago, James said:

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See what happens when you mix RAM DIMMS from different manufacturers!

 

 

 

I think my memory is different speeds and brands... got free parts. Have AM3+ setup. The ram is Sniper 1600mhtz and Ripjaws that is even lower I believe...

[FakeFBI]

3 minutes ago, 2DPrinter said:

I think my memory is different speeds and brands... got free parts. Have AM3+ setup. The ram is Sniper 1600mhtz and Ripjaws that is even lower I believe...

ddr3 never gets affected if at same speed, ddr4 though

EDIT: with my expiriences ofcourse

[Valde]

I have a system of 2x8GB 2667MHz sticks, I'd like to add another 8GB of RAM, could I go for a single 8GB stick or should I go for 2x4GB sticks? (different brand possibly)

[Gum Joe]

In my system I have 2x8GB of Corsair Vengeance 2400 MHz, and 2x8GB Corsair Vengeance RGB 3200 MHz (same CAS latency I think).  They run fine together (using the 2400 MHz XMP profile), but when I attempted to overclock the 2400 MHz to 3200 MHz the system just wouldn't boot - but this could be because I was overclocking wrong (I just went and typed in "3200" into the box for memory speed).  MoBo is ASUS Z270-A. 

[Razor512]

For mix and match DDR4, most of the issues when lowering clock speeds is not achieving stability, comes from tertiary timings, for example, if you mix Samsung B die with a low binned B die from micron, You could end up with your board using the B die tRFC values from the Samsung kit on the Micron kit, which can cause you to continuously fail to boot, even at low clock speeds, due to Samsung B die having significantly lower tRFC timings.

 

Outside of that, at long as the timings are close enough between the kits, you can get away with a lot of mixing and matching, but you may end up having to specify the tertiary timings for some of the key values that are far apart, and set them to the match that of the worst kit on the channel.

[prudhvi]

my PC has 8G DDR3 1600Mhz Kingston ram, I have an extra 8G DDR3 1333Mhz Samsung ram can I mix them?

[prudhvi]

my PC has 8G DDR3 1600Mhz Kingston ram, I have an extra 8G DDR3 1333Mhz Samsung ram can I mix them?

[Razor512]

Just now, prudhvi said:

my PC has 8G DDR3 1600Mhz Kingston ram, I have an extra 8G DDR3 1333Mhz Samsung ram can I mix them?

 

Possibly, first check the timings of the 1333MHz kit, as well as the DRAM die type. If needed look at the auto detected timings. Test each kit individually, then try both at the same time. If it struggles to boot, then start forcing some of the timings to match that of the loosest timing kit, especially the tertiary timings. Then try both sticks again. After that, experiment with seeing how high you can push the clocks for the 1333 kit. You likely will not get it to 1600 speeds, but you may be able to find some middle ground.

[PeachGr]

(after i saw the video)
I believe there is a reason that they sell ram sticks as twins when you buy 2 of them and not 2 on separate packages, as they do with fans
My guess was always that there is a small chance to fail that RAM manufacturers don't want to deal with, so they test them together to match them
Well it could be a compatibility issue back is the DDR2/3 era, and they keep it as such for the peace of mind

[Radium_Angel]

I've mixed and matched before with no ill effects, but these were not gaming systems.

My main (soon to be only) rig is populated with 16 sticks of identical 4GB ECC Registered DDR3 RAM, CL 9. Woo.

[RejZoR]

MEMORY CAPACITY > MEMORY SPEED

 

The benefits of just having more RAM available to work with will ALWAYS outweigh any speed loses. Coz when you run out of memory, not even 90000000000000 MHz RAM can help you. But having so much RAM that nothing ever runs out of it is a very different story.

 

I had X58 based system that had triple channel memory. And I was running it in 18GB configuration. 3x2GB sticks and 3x4GB sticks in symmetrical arrangement. And that's what's important. Don't just stick them in like a hooligan. Symmetric arrangement across channels is the key to consistent and reliable operation, even if you mix and match different sticks. Coz that meant all 3 channels had identical memory to work with. Probably wasn't ideal speed wise because I remember I had Corsair Dominator and TeamGroup Elite sticks mixed, both at 1600MHz (DDR3), don't remember about timings, but I had 18GB of RAM back when most people didn't even have 8GB in total. In triple channel. I didn't even care how much memory anything consumed.

 

Same would apply for dual channel too. Like 2x2GB and 2x4GB, totaling unusual 12GB of total memory. But it would totally function and probably very well if each channel ends up having 6GB of RAM and with same primary and secondary arrangement per channel.

 

Given most users run systems with 4 slots and in most cases run it in single or dual channel with minimum allowed number of sticks, expansion really isn't that difficult. Sticking 4000MHz sticks next to 2133MHz ones is absurd and no one will do that from pricing perspective alone. Finding something closer in clock generally shouldn't be an issue.

[Collin_S]

I have been quite curious about this recently... I have a 3900x + MSI MAG X570 Tomoahawk and I currently have a 2x8 GB kit of Crucial Ballistix DDR4 3200 CL 16. I have been thinking about upgrading it with a 16GB stick of Crucial Ballistix DDR4 3200 CL 16, putting me at 32GB, but giving me the option of upgrading again down the line if I needed more, which I would think of doing with another of the same stick. So that would end up with (all Crucial Ballistix DDR4 3200 CL 16) 2x8 GB + 2x 16 GB sticks, probably arranged so that there is an 8GB stick and a 16 GB stick in each channel.
 

It sounds like this could work according to the video, but I would just like to double check.