780 MT, adding RAM

Question

Hi, I'm attempting to add at least 8GB of RAM to an Optiplex 780 MT.  I have the below 8GB stick but when I insert it and turn on the computer, lights 3 and 4 are on and the computer won't boot.  I'm assuming there is a compatibility issue with the RAM.  I was told by a Dell rep that the Crucial brand is most compatible with Dell computers.   https://www.amazon.com/dp/B008KSHQBU/ref=cm_sw_em_r_mt_dp_U_MUiUCbXJ786M3 Do I need two 4GB stickers to get 8GB or can I use a single 8GB stick?  Am I able to mix brands?  Right now, there are two 2GB Samsung sticks installed.  Can I add a single 8GB with an existing 2GB stick to make 10GB?  Please advise.

speedstep · Answer

8 GIG modules are not supported. Max ram is 16 NOT 32.

Slots: 4 (2 banks of 2)

Maximum Memory: 16GB

Ram cannot be QUAD RANK.

Ram cannot be HIGH DENSITY

Ram cannot be ECC or Registered or buffered.

https://www.crucial.com/usa/en/compatible-upgrade-for/Dell/optiplex-780-desktop

DDR3 PC3-12800 • CL=11 • UNBUFFERED • NON-ECC • DDR3-1600 • 1.35V • 512MEG X 64 •

Crucial works and there are other compatible vendors.

https://www.amazon.com/Timetec-1333MHz-PC3-10600-Unbuffered-Optiplex/dp/B071Z7BD2T/

BJM124 · Answer

Thank you for the reply.  However, the 780 that I have only has two slots.  Therefore, the max amount is 8GB (2 sticks of 4GB)?

bradthetechnut · Answer

The GX520 also only came with 2 DIMMs.  The 380 MB is a little shorter and doesn't reach the bottom of the case.

bradthetechnut · Answer

As far as 780's go, only the USFF has only 2 DIMM slots. Also, the 380 has only 2 DIMM slots, all sizes. It makes me wonder if you have a different model other than what's stated, possibly sold to you with a different badge?

If it helps, 1st screengrab is from 780 Tech Guide, and the 2nd one from 380 Tech Guide. The 380 is just one example I thought of right away that came with 2 DIMM slots.

Images of MB's can be Googled. Be sure to specify "MT" as you did here. You can see if the image matches your MB.

Optiplex 780

Optiplex 380

bradthetechnut · Answer

I found what looks like a couple of 780's on eBay that only come with 2 DIMMs. I didn't know they existed. The 780 is suppose to be a step up from 755 and 760, which come with 4 DIMMs.

EBay Optiplex search

EBay Optiplex 780

Edit: After I made this post, I double-zoomed in on the MB that's in the 780 referenced in the links. I zoomed in, screengrabbed it so I could zoom in further, and took another screengrab. The black tabs that are harder to see at first, that hold the chips are there, besides the white ones. It looks like this model still has 4 DIMMs.

One of our Rockstars or other experts, if they decide to chime in, might have a better idea if a 780 MT was ever made with 2 DIMMs.

Capture+_2019-04-18-23-23-06.png

I didn't notice right away edges were trimmed on photo above. Can't delete photo once added.

speedstep · Answer

2 Slots is Desktop, SFF, USFF.

8 gigs is max for those.

http://i.dell.com/sites/content/business/solutions/engineering-docs/en/Documents/optiplex-780-tech-guide.pdf

Must be Low Density

Must not be ECC

Must not be Registered or Buffered.

Must Not be QUAD RANK

https://www.amazon.com/Crucial-240-Pin-Desktop-Memory-CT2KIT51264BA1339/dp/B003GJL5U6

https://www.amazon.com/gp/offer-listing/B003GJL5U6/ref=dp_olp_0?ie=UTF8&condition=all

desktoptechguy1112 · Answer

Put 2 4gb ram sticks into both white slots. It will not take 8gb in one white column, it needs 2 4gb ram sticks in both white columns, same for the black columns

Optiplex Desktops

Was this post helpful?