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Re: more than 12G of RAM

On 10/02/14 11:24 AM, Dave Woyciesjes wrote:

On 02/09/2014 10:14 AM, Jerry Stuckle wrote:

On 2/9/2014 8:27 AM, Gary Dale wrote:

On 09/02/14 06:50 AM, Stan Hoeppner wrote:

On 2/9/2014 3:32 AM, Efraim Flashner wrote:

On Sat, 08 Feb 2014 10:20:49 -0500
Gary Dale <garydale@torfree.net> wrote:
I'm running Jessie on an AMD64 Gigabyte 970A-D3P board with an FX6100 
processor. I had 2x4G DDR3 sticks in it but some of the programs I
use were causing excessive thrashing. I added a 1x8G DDR3 stick (got
a good price on it, much cheaper than adding 2x4G) which resolved the 
thrashing problem.
The BIOS shows I have 16G but free shows only 12G. I also ran free on 
a machine with 2x8G DDR3 running Wheezy and it showed 16G when I ran
free. This suggests that the kernel is handling 16G (as one would
expect) in the general case and the issue is likely due to my setup.

Since the BIOS shows the full 16G, the problem doesn't seem to be on
the mainboard. Is there an issue with running interleaved and
non-interleaved RAM together on the Jessie kernels?
It sounds to me like you have some issues between your two sets of ram, 
the 8G stick and the 2x4G sticks.  Is there a difference in
timings/speed/voltage? I've never put much stock in people saying that you shouldn't mix different types of ram if the price is right, but you 
might need to change around the placement order.  Assuming the
motherboard supports dual-channel ram, I'd make sure you have the 2x4G 
sticks paired up and the 8G stick on its own channel.


According to page 16 of the manual you have an unsupported memory
configuration:
http://download.gigabyte.us/FileList/Manual/mb_manual_ga-970a-d3p_e.pdf
If this combo will ever work, the first step is to verify the 8GB stick 
is in one channel and the two 4GB sticks in the other.  If you still
don't see all 16GB then disable rank interleaving. If that doesn't fix it, disable channel interleaving. If that doesn't fix it, you may be of 
luck, and will need to either swap the 8GB stick for a pair of matched
4GB sticks, or acquire another identical 8GB stick.
That page just tells you how to install dual-channel DDR3 sticks. Again, 
the BIOS detects the full 16G. This shows that the setup does work with
the board.
"Detected" and "Working" memory are two entirely different things. It is perfectly possible for your BIOS to detect 16GB, but 4GB of it not work properly. 

Both Stan and Efraim have good comments.  I suggest you follow them.

Jerry



Have you run memtest yet?
Yes. After the other comments, I gave it a try. It also only sees 12G. I find this confusing in that the board apparently works with a mixture of interleaved and non-interleaved memory - as witnessed by the fact that I'm running that way. Why should it see the non-interleaved module as only 4G instead of 8G?
The board has 4 sockets and according to the specifications supports up to 32G of memory, which means it should support 8G modules. I could understand the problem if it only supported 4G modules, then it might only see part of the extra memory. I could understand it also if the configuration simply didn't work and only showed me 8G total. 12G I don't understand.
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