We have Optiplex 780 mini-tower machines at work, and for the last couple of days want to upgrade them to the maximum memory possible. It's next to impossible to find an easy answer to what is the maximum memory is for these machines.
Dell specifications - http://support.dell.com/support/edocs/systems/op780/en/SM/SM_MT/specifications.htm - say it's 8GB DDR3 1066GHz
Two other documents on Dell website have 16GB as max memory.
Dell Optiplex 780 tech guide pdf (http://i.dell.com/sites/content/business/solutions/engineering-docs/en/Documents/optiplex-780-tech-guide.pdf) - page 9, and Dell Optiplex 780 Setup and Features Guide pdf (http://support.dell.com/support/edocs/systems/op780/en/SFITS/SFITS_Al/SFITS_EN.pdf) - page 7
Anyone knows what's the correct information?
Size - 8GB or 16GB?
Which speed - 1066GHz or 1333GHz?
The MT will support up to 16 GB fine. Best bet is to get 2×(2×4 GB kits) from crucial for each machine. The part is here. Crucial memory is the best for Dell systems.
The link that mentioned the 8 GB only probably just meant the USFF and didn't list all the units seperately as the tech guide pdf does.
We tried upgrading to 16GB, using Mushkin memory: www.mushkin.com/.../993770.aspx , and the machine did not want to boot, it was bluescreening, and we even tried reinstalling Windows, and it did not work.
Why would Crucial memory work?
You were right, Philip, Optiplex 780 Mini-Tower accepts 16GB of DDR3, 1333Mhz.
Our problem was that 2 DIMM modules (out of 8) were defective. In all the discussion on what to do, we did not look at the diagnostics lights on the Mini-Tower case, to tell us what's wrong. Dell actually has a very helpful diagnostics document, support.dell.com/.../diags.htm . We had lights 3 and 4 on, and from that we realized what's going on.
Thanks for your help Phillip, and I am marking your answer as helpful, since you confirmed that 16GB has to work. Once we knew that, we looked at other possible troubleshooting paths that led us to solving the problem.
Glad you got it resolved, I recommend crucial because it has always worked for me with Dell systems.
Most other users on these boards also prefer crucial as the Dells seem to prefer crucial RAM and there is usually less problems with crucial RAM.
We have found that other companies RAM does not always work as well or some of the modules are bad or alternatively only some of the modules work and some users reported that they can't boot if they have 4 modules (non-crucial) yet can if they use and 2 of the 4 modules only.
Is there anyway to upgrade to 16GB with a 32 bit processor?
32 bit is limited at 4 GB of RAM.
If you install 16 GB of RAM on a 32 bit OS only 4 GB at maximum will be read.
You will need to upgrade the processor and switch the OS to 64 bit aswell as upgrade the RAM in order to upgrade to more than 4 GB.
Thanks for sharing your expertise; it was very helpful!