Hi Enigmothy,

Both Crucial and the spec sheet for the Opti 390 say 8GB (2x4GB). Of course, you're welcome to try 2x8GB and let us know if it works.

Updating this thread to confirm that the Optiplex 390 does indeed support 16GB (2 x 8GB DIMMS) of memory.

The memory in question is G.Skill DDR3-1600 PC3-12800 8192MB x2 (F3-1600C11D-16GNT) set.

Cheers.

Hi could you tell me if that RAM upgrade to 16gb is available in any 2x8gb RAM chip formations of the same spec i.e. DDR3-1600 PC3-12800. Meaning like from some other manufacturers like Crucial or Kingston etc?

Hi I would like to update this thread for the sake of helping others. I recently installed 16gb (2x8gb sticks) of RAM in my Dell Optiplex 390 Desktop and it seems to accepting the full 16gb. I checked both the BIOS and Windows specifications page and it says that the full 16gb is in use.

The RAM modules I purchased where http://www.amazon.co.uk/gp/product/B00A14ZTRO?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

Crucial Balistix Tactical LP 16gb (2x8gb) - Ballistix Tactical BLT2C8G3D1608ET3LX0CEU 16GB kit (8GB x 2) DDR3 PC3-12800 Unbuffered NON-ECC 1.35V.

The memory speed has been slowed down to 1333mhz by the motherboard I think and I have no way of changing the XMP profile to run it at 1600mhz due to the limitations of the board. I can confirm however that in 1333mhz mode my computer is running really fast and I can't complain whatsoever really. My computer has the Core i5 2400 processor in it and the stock 250gb HDD just to clarify.  

can i add to this del a gtx graphic card?

hi all

I got bios A11  on my optiplex 390 and  I need memory upgrade  right now i got 8GB  2x4GB

i saw  ram modules like this

www.itcsales.co.uk/.../Dell-Certified-8GB-System-Memory---Dual-Rank-PC3-12800U-11-13-DIMM-1-5V-13903.html

will they work at  optiplex 390 as 16 gb  ?

Thanks.

I was also able to get 16gb working with an i5-2400 and bios updated to A11.

Here is the memory I used: Crucial 16GB Kit (8GBx2) DDR3L 1600 MT/s (PC3L-12800) Unbuffered UDIMM Memory CT2K102464BD160B

So you are saying that for the Optiplex 390 ram 16 gigs is possible with this specific ram.  Ballistix Tactical LP 4GB Single DDR3 1600 MT/s (PC3-12800) UDIMM 240-Pin Memory - BLT4G3D1608ET3LX0CEU

http://www.crucial.com/usa/en/ct2k102464bd160b

The Spec is very important.

DDR3 PC3-12800 • CL=11 • Unbuffered • NON-ECC • DDR3-1600 • 1.35V • 1024Meg x 64

 CRUCIAL HOWEVER SAYS ITS NOT COMPATIBLE.  Unless you verify it works they WILL NOT RMA the ram.

This is the ram they list as compatible.

DDR3 PC3-12800 • 9-9-9-24 • Unbuffered • NON-ECC • DDR3-1600 • 1.5V • 512Meg x 64 •

http://www.crucial.com/usa/en/optiplex-390-mini-tower/CT5289288

so I Can confirm that kingston 2x * 8GB is working with dell optiplex 390 DT I also changed CPU for i5-2400 is some one have better CPU that can work with that mainboard I will be interested. Grapic card is quadro p620 2gb ram So I can confirm that this RAM modules also working : 

 Kingston KHX1600C9D3/8GX

Memory slots
Total memory slots 2
Used memory slots 2
Free memory slots 0
Memory
Type DDR3
Size 16384 MBytes
Channels # Dual
DRAM Frequency 669.7 MHz
CAS# Latency (CL) 9 clocks
RAS# to CAS# Delay (tRCD) 9 clocks
RAS# Precharge (tRP) 9 clocks
Cycle Time (tRAS) 24 clocks
Command Rate (CR) 1T
Physical Memory
Memory Usage 64 %
Total Physical 16 GB
Available Physical 5.64 GB
Total Virtual 50 GB
Available Virtual 32 GB
SPD
Number Of SPD Modules 2
Slot #1
Type DDR3
Size 8192 MBytes
Manufacturer Kingston
Max Bandwidth PC3-10700 (667 MHz)
Part Number KHX1600C9D3/8GX
Serial Number 6B0880D3
Week/year 40 / 13
SPD Ext. XMP
XMP-1600
Frequency 800 MHz
CAS# Latency 9.0
RAS# To CAS# 9
RAS# Precharge 9
tRAS 27
Voltage 1.500 V
JEDEC #4
Frequency 685.7 MHz
CAS# Latency 9.0
RAS# To CAS# 9
RAS# Precharge 9
tRAS 25
tRC 34
Voltage 1.500 V
JEDEC #3
Frequency 609.5 MHz
CAS# Latency 8.0
RAS# To CAS# 8
RAS# Precharge 8
tRAS 22
tRC 30
Voltage 1.500 V
JEDEC #2
Frequency 533.3 MHz
CAS# Latency 7.0
RAS# To CAS# 7
RAS# Precharge 7
tRAS 20
tRC 27
Voltage 1.500 V
JEDEC #1
Frequency 457.1 MHz
CAS# Latency 6.0
RAS# To CAS# 6
RAS# Precharge 6

Another working setup with 16 GB RAM:

SiSoftware Sandra (Edited)

System: Dell OptiPlex 390, Version 01

Mainboard: Dell MPS Version : 1.40, Model : 0M5DCD, Version : A00

Memory Type: DIMM DDR3 Version : 1.1.1.1

Bank 0 : 8GB DIMM DDR3 9-9-9-24 4-33-10-5 1T

Bank 2 : 8GB DIMM DDR3 9-9-9-24 4-33-10-5 1T

Max Memory : 32GB Channels : 2 Width : 128-bit Bus Speed : 2x 667MHz (1.33GHz) Max Speed : 1.33GHz

Memory Modul: Corsair CMZ16GX3M2A1600C9, 8GB DIMM DDR3

Technology : 8x(4096Mx8) Speed : PC3-12800U DDR3-1600

Monitor Standard Timings : 9-9-9-25 4-33-10-5

LPC Hub Controller 1: Dell H61 LPC Controller, Revision: A5

Processor: Intel Core(TM) i3-2120 CPU @ 3.30GHz, 2 Cores, 4 Threads

Socket/Slot: FC LGA1155

Multiplicator : 33x Kleinster/Größter/Turbo

Multiplikator : 16x - 33x

Front Side Bus Geschwindigkeit : 100MHz

Generation : 8 / 21 / 0 Revision/Stepping : 2A / 7 Stepping Mask : D2/J1/Q0

Microcode : MU062A0729, Most Recent: MU062A072E

Max physic. / virtual Address Range : 36-bit / 48-bit