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OptiPlex 990 memory upgrade greater than 8GB

Dear All,

I have a OptiPlex 990 (early 2011) SF form factor - it was delivered with 4GB memory (2x2GB Dimm).

Yesterday I wanted to upgrade memory to 16GB. The techbook says 4x4GB Dimm is supported.

I ordered Kingston memory KTD-XPS730BS/4G, which are supported according to the Kingston website.

When I installed all 4x4GB Dimm, the OptiPlex turns on, but won't boot, if I remove 2 DIMM from slot 3 and 4 the computer boots and the BIOS shows 8GB memory.

I upgraded the BIOS to A18 then I inserted the other 8GB again, but the computer didn't boot either. I had to remove DIMM in slot 3 and 4 again.

My question, what could be the problem that 16GB is not supported or DIMM 3 and 4? What else could I test. Somewhere I read it could be a power supply issue.



4 Replies

RE: OptiPlex 990 memory upgrade greater than 8GB

Hi ,

In this case I would ask you to confirm if these troubleshooting steps were tried .

*)What happens to the system when we populate the slots 1 and 3 with 2 DIMM'S similarly does the system boot when slots 2 & 4 are populated with again 2 memory modules.

*)Also here it seems to be a conflict with the frequency of the memory modules ,hence confirm if all the 4 DIMM are of the same make , frequency and speeds .

Awaiting your reply.If there are any more queries do reply to this community thread we will be glad to resolve them for you .

Kindest Regards,

DELL-Jennifer K
Social Media and Community Professional
Manuals and Drivers

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RE: OptiPlex 990 memory upgrade greater than 8GB

The ram you ordered only works on NVIDIA Chipset and is HIGH Density.  Its also too Slow being PC3-10600 DDR3-1333 NOT PC3-12800 DDR3-1600.  That ram is NOT INTEL Low density compatible. Voltage, Speed, Ranks, ECC or not, Buffers etc are all important.

DDR3 PC3-12800 • 9-9-9-24 • Unbuffered • NON-ECC • DDR3-1600 • 1.35V • 512Meg x 64 • Low Profile •



The ram goes in pairs based on the ejector ears so its not 1 2 3 4 but rather 1 3 then 2 4. Keeping all the same vendor and speed is also required.  Lastly you cannot use Quad Rank Ram and it must be Low Density and not be registered or Buffered. Largest Single Dimm size is 4 NOT 8 gigs.  4 X 4 Gig dimm = 16 total. The WHITE Ears are 1st bank the BLACK 2nd Bank


 PC3-12800 Unbuffered NON-ECC 1.35V 512Meg x 64


  • DDR3 PC3-12800 • 9-9-9-24 • Unbuffered • NON-ECC • DDR3-1600 • 1.35V • 512Meg x 64 • Low Profile •

Maximum memory: 16384MB
Slots:4 (2 banks of 2)


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RE: OptiPlex 990 memory upgrade greater than 8GB

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RE: OptiPlex 990 memory upgrade greater than 8GB

it is so weird that one new egg reviewer says about KTD-XPS730BS/4G:


Product is Great, First Seller was Overpriced

Pros: Good RAM. I have installed 32 sticks in 16 Dell 990s and have not had a problem.

Cons: When I went to purchase the first pair off the Newegg website, purchasing from Newegg was not an option. So I bought 2 sticks of RAM from TekEnvy. While the product was fine and delivery was quick, 1 stick of RAM from TekEnvy was $48. Fortunately, NewEgg got it back in stock, and I was able to buy the next 30 sticks direct from Newegg at $41 per stick.

Other Thoughts: I gave 4 eggs instead of 5 because Newegg was initially out of stock, and I saw no indication as to whether they would be replenishing their inventory. "

in here:


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