My Optiplex 780 SFF currently has 2 x 2Gb Dell (Samsung) Memory boards in white Slots DIMM1_1 and DIMM1_2
When I attempt to add a supposedly compatible SK hynix HMT451U6AFR8C-PB NO AA 1306 T (4Gb) to either of the black slots DIMM1_3 or _4 there is a rapid tapping noise in fits and starts and the computer doesn't boot FreeNAS. (which does boot OK with the original Dell memory).
Is it allowable to mix one 4Gb board with two 2Gb boards? If so does the board order in the slots matter?
Or is the hynix memory incompatible or likely faulty?
Any help greatly appreciated
Solved! Go to Solution.
Dell OptiPlex 780 SFF is compatible with only DDR3 SDRAM (non-ECC memory only) of clock speed 1067 MHz or 1333 MHz.
I see that you are trying to upgrade the memory having 1600 MHz clockspeed which would not be compatible with this systemboard.
You can mix 4GB and 2GB memories on the system.
Thank you very much for your prompt answer. I was unsure about the 1600MHz - wondered if it was backward compatible as the 1333 is usable even though it only runs at 1066 because of chipset limitations.
And I take it it doesn't matter which slots are used in what order? (and no jumpers?)
I have two Dell Optiplex 780's each with 2 x 2Gb of RAM. Both work just fine with their original memories.
I have decided to retire one of them (for the time being at least) and transfer its memory the open (black) slots on the second one.
However, when I do this (with all the precautions of many years dealing with computer innards), the second one won't boot at all.
I can't even get to the BIOS. Just makes a big fan sound.
Are there some jumper settings or something sneaky of which I am unaware?