# Going from 16GB to 32GB RAM - compatible?



## dvl@ (Dec 21, 2014)

One of my servers is running up swap on a regular basis.  Tonight, for example: 14% free (277 MB out of 2047 MB) [278 (14%)]

I have more than once selected the wrong RAM so I'm seeking second opinions please.

Current RAM: 2x Samsung DDR3-1600 8GB/1Gx72 ECC Samsung Memory – M391B1G73BH0-CK0

I have found: Kingston 16GB (2 x 8GB) 240-Pin DDR3 SDRAM ECC Unbuffered DDR3 1333 Server Memory Model KVR1333D3E9SK2/16G

Are they compatible?

server details: https://dan.langille.org/2013/08/18/slocum/


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## Terry_Kennedy (Dec 21, 2014)

dvl@ said:


> I have more than once selected the wrong RAM so I'm seeking second opinions please.
> 
> Current RAM: 2x Samsung DDR3-1600 8GB/1Gx72 ECC Samsung Memory – M391B1G73BH0-CK0
> 
> ...


The Samsung part is DDR3-1600 (CL11) per the datasheet. The Kingston part is DDR3-1333 (CL9) per its datasheet. That means the Kingston is a slower part. Your "server details" link omits the actual motherboard brand/model. It may be that your system is running the memory at a lower speed and the Kingston will work. Or, it is running at 1600 and will slow down to 1333 when the new memory is added (all memory runs at the speed of the slowest module in most systems). Or, it won't work at all because the system needs 1600 - it is impossible to say without knowing the board. I took a quick look around the Kingston site and it seems that the KVR16E11/8 would be a match for your existing memory. That's a single 8GB module, so you'd need 2.

Bear in mind this is free advice and worth every penny you paid for it. Your best bet would be to enter the actual motherboard brand/model into the Kingston product selector here and see what it tells you.


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## dvl@ (Dec 21, 2014)

Terry: I've added a link to the server description to that URL.

The motherboard is a SUPERMICRO MBD-X9SCL+-F which can take 1333/1600MHz.

The Kingston product selectors gives this range and the KVR1333D3E9SK2/16G mentioned above is listed there.

I like your assessment and the recommended RAM, which comes on two varieties:

KVR16E11_8HB (2.119 W) & KVR16E11_8KF (2.268 W)

The only difference between the two appears to be maximum power consumption and the price difference ($5).

Quick math, says saving 0.149W per hour at 8.84 cents per KW/H is an annual savings of $0.12 per stick.  It would take 41 years to recoup the cost.  

I'll go with the higher power RAM.

Thank you.  This is why I never do RAM on my own.  I appreciate the help.


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## User23 (Dec 22, 2014)

If you don't need to, you never mix different RAM types. IMHO especially not on servers, because I don't like to add possible sources of trouble to the hardware.


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## dvl@ (Dec 22, 2014)

User23 said:


> If you don't need to, you never mix different RAM types. IMHO especially not on servers, because I don't like to add possible sources of trouble to the hardware.



I think this is sound advice. However, I ordered the new RAM (Kingston) last night.  I went with mixing RAM because the original wasn't in stock with my usual sources.  Checking now, I see it on eBay.


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## dvl@ (Dec 24, 2014)

The RAM showed up.  One stick at a time about a 50 minutes apart.


```
real memory  = 34368126976 (32776 MB)
avail memory = 33130627072 (31595 MB)
```

I also took the opportunity to add in two 30GB SSDs.  They'll be added into the ZFS mixture soon.


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## Terry_Kennedy (Dec 25, 2014)

User23 said:


> If you don't need to, you never mix different RAM types. IMHO especially not on servers, because I don't like to add possible sources of trouble to the hardware.


For buffered or registered memory, I agree - there can be subtle differences between manufacturers, and the systems that use those tend to have advanced memory controllers that like to interleave many memory modules. But for regular unbuffered memory, as long as it is the same speed and latency (CLx), things should be interchangeable. The only place you can run into trouble is single- vs. double-rank memory, which is why I went back to the actual datasheet for the memory dvl@ had in the system.


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## dvl@ (Dec 25, 2014)

Uptime is just past 23 hours. All seems well.  Thanks all.


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