I tried up upgrade my memory from 8 GB to 16 GB with the following memory:
1 of: 16GB (4x4GB) Memory RAM Compatible with Dell Optiplex 980 DDR3 DIMM BY CMS C58
Sold by: Computer Memory Solutions
When I turn the computer on, after 8 seconds I get 6 audio beeps and front the panel amber numbers 3 & 4 remain lit constantly. The ON/OFF switch has no effect. It looks like there is a small led lit inside the computer and looks to be labeled Aux Pwr.
I removed the New Ram and re-installe the original 8 GB and now my computer works. Once more to double check I put the 16 GB back on and again I get the same problem.
Suggestions anybody? Thanks.
What model Optiplex do you have and what size? - MT, DT, SFF, or USFF?
Try keeping your original 8GB in and then installing 2x4GB of your new memory in the two secondary slots. If it doesn't work the first time, try the other 2 sticks, and if that doesn't work, try a few different combos.
The reason is that one of the new memory sticks may be faulty, and causing all the problems, and this gives you a way to identity that. If you try the above, and keeping your old memory installed, then switch the two pairs around (4x combos) then that will prove it pretty quick.
That isn't a perfect solution, but at least it will give you more evidence on whether the new memory is compatible or maybe a stick is bad, .
Also, just confirming you have also upgraded to the latest BIOS? If not, then please do so using the old 8GB that works.
Here is an old thread that covers your problem off, although BIOS updates since then may have smoothed some of these issues:
Tip: Make sure all the sticks are the same brand, capacity, and MHz. Crucial is guaranteed to work in Dell's. Kingston Value Brand (KVR) almost never works. The volts can be off in off-brands.
This isn't just Dell, but other brands as well. One of our Rockstar's can use 2 different brands in his custom built Asus (also has a Dell), but can only use the brands one at time.