Re: more than 12G of RAM
On Tue, Feb 11, 2014 at 1:58 PM, Gary Dale <garydale@torfree.net> wrote:
> [...]
> Sorry, but it still makes very little sense. When I turn off interleaving,
> the BIOS should try to access all the memory 32bits at a time. This would,
> one should expect, allow the memory to be accessed in full.
Okay, you understand more than I was giving you credit for. Sorry about that.
However,
> Your suggestion that it is the 8G + 1x4G which is being recognized
Not quite what I was trying to suggest. I was oversimplifying significantly.
> leads to
> an interesting idea - putting the 8G in the same channel as one 4G stick may
> allow the full memory to be recognized, if only at 32bit speed.
Uh, no. Don't do that. I don't know the odds, but it could well result
in permanent regrets.
> I'll have to try it, but I'm not hopeful. If it was the case, why would it
> lose an entire memory stick?
Well, the point I was trying to make is that the circuitry that is
sensing and remapping your RAM is pretty complicated. If you have
designed memory selection and refreshing circuits in the past, I could
point to certain issues like race and current drain and isolation. One
map is not so hard, but the RAM slots are supposed to take a variety
of sizes and timing, and all of those have to be correctly decoded and
refreshed.
Even though the sale where you bought the 8G stick is over, I'm
thinking I'd see if I couldn't order one of the same type directly
from the manufacturer. Unless the manual says 2 and 1 should work, in
which case I'd still try to get a mate for that 8. You said elsewhere
that the compatibility table didn't list 8G, so what I'm saying is you
basically you take what you get. You are outside the specs, so nothing
should be surprising.
> I suspect that nothing about this makes sense and that the BIOS programmers
> just assumed that an even number of slots would be occupied if you had more
> than one stick and messed up the 3-stick case.
Does your motherboard manual say it'll take a pair-and-single configuration?
Put bluntly, I'm not only surprised it doesn't fail POST with 2x4+8,
but I would hesitate to run it that way for extended periods of time,
unless your manual says it's supposed to handle such a configuration.
> The kernel relies on the
> BIOS, as Stan Hoeppner reports, and so Linux fails to recognize all the RAM.
--
Joel Rees
Be careful where you see conspiracy.
Look first in your own heart.
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