02-13-2012 12:11 PM
I purchased additional memory for my D20 ThinkStation. I now have six 4GB memory modules, all the same, and all purchased from Lenovo.
They are obviously recognized, because the system panel in Windows indicates 24GB, however only 16.0GB is available. I am sure the modules are seated correctly. (Actually how could they be recognized if not seated correctly. Nevertheless...)
I have read that a re-flash of bios might help, but do not know how to do that. I originally had 12GB, and all was OK, but since adding another 12GB, only 16GB is recognized.
Are there settings within my computer which will correct this memory issue? Any suggestions?
02-13-2012 12:21 PM
if both your BIOS and system properties report all 24GB and you don't get any beeps on boot, your system is normal.
with 24GB in my C20 i'm lucky to have 8GB "available" while working with multiple heavy applications. this is to be expected. keep in mind that windows will free up unused space when demanded. after all, unused memory is wasted space.
take note if the 16GB changes or remains static. i'd bet it changes once you open a few large apps.
if you're unsure, please post a screenshot of your task manager and a list of applications in use at the time.
02-13-2012 12:52 PM
Oh, Ok. Thanks Erik.
There are no beeps when booting up, all normal there.
I will keep note of usable memory, try to bog down my machine, see if it changes when opening video editing software and other tasks. I simply assumed all memory would be available, since it was all available before when I only had 12GB, even when no software was open and running on my machine.
Just to be sure, you are saying that if my software demands more memory, that Windows will "ramp up" and should show more usable memory than what is currently shown, which is 16GB usable, even though 24GB is installed?
I will respond back one way or the other.
02-14-2012 05:41 AM
i missed the detail about "usable" vs. "available" and there's a big difference in that nomenclature.
by chance are you using windows 7 home premium? if so, it's limited to 16GB per microsoft's specs.
here's a good article about memory: http://support.microsoft.com/kb/978610
with 24GB in my C20 under server 2008 R2 enterprise SP1, all 24GB are usable. availability, however, fluctuates.
02-14-2012 06:17 AM
I am using Windows 7 Professional. I have seen the memory limitation with Premium, but that does not apply to my situation.
Somehow I believe there should be a method to allow all 24BG to be usable, not simply available.
02-14-2012 09:02 AM
just for kicks, pull all six modules out and reseat them. make sure they go in with even pressure on the sides and the locking bars engage simultaneously. it's possible that one didn't get seated correctly and knocked out its adjacent module, taking you from 6 x 4GB to 4 x 4GB.
if that doesn't work, try switching the order to see if anything changes.
02-14-2012 09:13 AM
Well, to be frank....if you have 24GB in a system, you'll never see a situation where all 24GB are "usable" or "available". BIOS needs some of this to do it's thing, and this will always result in the OS reporting back a lower amount than what is actually installed in the system. How much lower can vary based on how well the code is written and how efficiently (or inefficiently) things are done.
The easiest check to do (and I think you might have already done this) is to check and see if BIOS is reporting all of the installed memory via the F1 setup screen. If the number showing in BIOS under system summary doesn't match what you have installed, then go the reseating route.
02-16-2012 08:17 AM
After calls to Lenovo tech support and a LOT of troubleshooting I have discovered the following:
As I add 4GB memory sticks, one at a time, booting and checking BIOS and Windows each time, all is OK up to three sticks, BIOS sees 12GB, and so does Windows System screen.
Next I added a 4GB stick to slot 4, (16GB total) now the BIOS sees only 8GB, and Windows confirms with 16GB installed memory but only 8GB usable.
Next I added a 4GB stick to slot 5, (20GB total) now the BIOS sees 12 GB, and Windows confirms with 20GB installed memory but only 12 usable.
Next I remove a 4GB stick from slot 4 since that is where the trouble started, (16GB total) and the BIOS and Windows see all 16GB. All working as it should. I have been told memory must be added in order, but here I have slots 1, 2, 3, 5, and machine working OK.
Next I added a 4GB stick to slot 6, (20GB total) and the BIOS now only sees 12 GB, and Windows confirms with 20GB installed memory but only 12 usable.
Next I added 4GB memory to all six slots (24GB total) and BIOS sees 16GB, and Windows confirms with 24GB installed but only 16 usable.
The bottom line is that for some reason slots 4 and 6 are causing this issue of "grabbing" memory for "Hardware Reserve". I suspect that somewhere, maybe on the mobo there is a jumper or switch or some way to turn this off. Lenovo should be able to help me with this, since they sold me this machine and I purchased my memory from Lenovo, but no one seems to have a solution.
One more odd issue, I placed three 4GB sticks in slots 1, 2, 3. Also two 2GB sticks in slots 4, 5. My machine had no problems, it recognized all 16GB.
I have read about this issue quite a bit and am unable to find a solution, but I know Lenovo is shipping machines with 24GB memory (and more), so seems someone might have the answer of what to tweak in the BIOS or maybe directly on the mother board.
Thanks for your advice so far.
02-16-2012 09:57 AM
what CPU do you have? is it a 5500- or 5600-series xeon? if it's a 55xx, i'm wondering if this has to do with how 5500-series xeons handle memory ranks. i'm also curious if your memory is dual- or single-ranked (or a mix). in theory, a 5500 xeon with single-rank memory should show all 24GB. a 5600 with any rank should also show all 24GB.
however, i'm making a WAG here based on my own fuzzy memory. hopefully psuturtle can chime in with some thoughts.
02-16-2012 10:13 AM
CPU is Intel Xeon 5660 @ 2.8 GHz.
I am not sure whether memory is dual or single ranked, not even sure what that means, getting over my head at this point.
It is the UDIMM memory available for purchase on the Lenovo web site, 4 GB, 1330.
Computer does show all memory as installed when I view the Windows system screen. The issue has been that only a portion of it is usable. The BIOS has only shown the usable portion, every time.
I am wondering if Intel could help, maybe they know something about this motherboard or BIOS. There are a lot of settings on the BIOS, most of them I have no idea what they do, nervous to go "experimenting" with them.
The computer is fast, but sure would like to have that extra memory I paid for up and running.