Mixing Identical Ram Kits in z620

[DasClueless]

Hello there.

 I am really needing a RAM upgrade for my z620 as having Substance Painter, Zbrush, and Maya (necessary when texture painting) open at the same time quickly overwhelms my 32GB of ram. It is currently in the form of 4 8GB Samsung M393B1G70QH0-CMA 1866 DIMMs and looking at the used market I found someone selling a new 64GB kit for about 500 dollars CAD compared to the hundred dollars per individual DIMM, BOO-YAH!

 Now here is the thing before I buy, is it safe to mix this kit with my own as they both use the exact same DIMM models but they are not matched. Will I suffer severe instabilities or given that it is higher quality RAM will I side step the issues normally associated with mixing identical RAM kits in so far as the size and model of the DIMMs themselves, not the actual size of the kits?

 P.S. I have the latest Boot Block date and 2 w2680 v2s.

 Thanks for the help!

[Brian1965 · Accepted solution]

Hi DasClueless,

I assume you mean the 64GB kit is 8 x 8GB modules? Providing you are using the same model/part no. of ram modules, e.g. Samsung M393B1G70QH0-CMA, then you definitely won't have any issues. 

You can mix ram modules of different sizes but I definitely wouldn't recommend mixing brands, e.g. Hynix, Samsung, etc.

With your dual CPU configuration you should really have been running with a minimum of 8 ram modules. i.e. each CPU has 4 memory channels, (and each channel has 2 lanes), and peak system performance is only achieved if all the available memory channels are used. The Z620 supports up to 12 ram modules (8 for CPU0, 4 for CPU1) and the Z820 supports 16 ram modules (8 per CPU). 

P.S. In my own opinion, the term 'matched' CPU's or memory modules is an urban myth and clever selling ploy. So long as you are using the same brand and model, you won't have compatibility issues. Samsung, Hynix, Kingston and the rest of them, wouldn't be able to sell their ram modules if they weren't compatible with their own brand of memory?

[DasClueless]

 You are correct in that the kit is 8x8GB and while I would have loved to have had such a setup with my dual processors; unfortunately I was strapped for cash after getting my z620 running. With the christmas season coming up and getting hours up the wazoo I am now able to add the kit to my computer. I just needed to know it was safe because I mixed two  G.Skill Ripjaw Z 32GB kits in the past when DDR3 was new and expensive (and I could only afford one at a time) on my old 3930K system and whenever a single program used more than 8GB of Memory it would crash. A light increase in the voltage on the RAM fixed the issue but obviously you cannot do that on this system.

 Thanks for the heads-up.

[MtothaJ]

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@Brian1965 wrote:

P.S. In my own opinion, the term 'matched' CPU's or memory modules is an urban myth and clever selling ploy. So long as you are using the same brand and model, you won't have compatibility issues. Samsung, Hynix, Kingston and the rest of them, wouldn't be able to sell their ram modules if they weren't compatible with their own brand of memory?

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@the problem with 'matching' only really comes into play if you are running RAM at overclocked settings - so for DDR3 at a frequency which requires more than 1.5V. In such instances there are cases when e.g. a 4x8GB kit of DDR3 2400mhz @ 1.65V runs fine, but adding an identical kit to fill all dimm slots results in having to go down to e.g. 2133mhz, whilst a matched 8x8GB kit would be guaranteed to function at this frequency.

Sometimes there is also the case that as time goes on - depending on pricing, market conditions etc. - manufactures switch their memory ic suppliers - sometimes this is clearly labelled (different part number, different version number) but not always, and the result could be that adding the 'same' brand RAM later on actually results in the unintentional mixing of ram from 2 different manufactures.

[Brian1965]

Since you are running a single CPU configuration you can only have 8 ram modules installed. If you have purchased a 64GB ram kit (8 x 8GB) then I would recommend you remove the current 32GB and place the 64GB ram on the motherboard. You should be able to sell your old ram modules. 

You cannot populate the CPU riser board with memory unless you have a second CPU installed.

[DasClueless]

 Huh? I already mentioned that I had two processors. The 32GB I have installed already is split into pairs on the mainboard and riser card, that is the configuration I bought it in before adding the 2 2680 v2s to replace the 2 2609 v2s or whatever they were.

[Brian1965]

Sorry, my mistake. I mis-read a previous post.

[DasClueless]

It's all good. 

[DasClueless]

Well there it goes.

 I ended up mixing Brands. Samsung M393B1G70QH0-CMA  and Hynix Semiconductor HMT41GR7AFR4C-RD. I did not notice until I almost finished installing the new sticks which is odd because they are fricking blue, FRACKING BLUE!!! Anyhoo, I booted up my system and... huh. Everything seems OK and they are all running at 1866. I opened up scene files and projects in excess of 8GB of RAM due to the act of spilling over onto another stick normally causes instability (in my experience) with poorly matched sets but lo-an-behold, no problems whatsoever.

 Oddly enough the factory sealed packaging is labeled as M393B1G70QH0-CMA so I did not think that much of it. I am contacting the seller with a sternly worded message and will withhold feedback until I can ascertain that I have full system stability. Is there anything anyone can think of that will determine if there are any issues with stability that might still rear its head in the future? I open up an unecessary number of scenes in Zbrush, Photoshop, Maya, Blender, and Substance Painter to use up to 56GB of RAM to see if all of the sticks were working (as I ended up only buying an extra 32GB) and everything seems hunky-dory, for now.