# [SOLVED] Dell Optiplex 755; picky with memory



## wkw427

I have two Dell optiplex 755s. They use DDR2 memory. Each came with 2x1gb sticks, so I wanted to put in two more 1gb sticks for a total of 4GB.

However, these 755s will _not_ boot with any other memory, aside from the total of four 1gb sticks that came between the two of them. The bios gives one long beep, repeating.

This is with _any_ ddr2 aside from the sticks that came with them. I can have 1, 2, 3, or 4 of the memory they came with, and it works fine. 

The memory in particular is "ELPIDA EDE11UD8AJWA-6E-E".

However, those same modules work in another DDR2 machine.

Does anyone have any ideas?


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## Tyree

*Re: Dell Optiplex 755; picky with memory*

What brand/specs are the new RAM? 
OEM Mobo's are commonly selective about RAM.
Crucial brand is he best option for OEM Mobo's.


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## wkw427

*Re: Dell Optiplex 755; picky with memory*

I've tried 

2GB Kingston KTD-WS667/2G
512mb Samsung M378T655CZ3
1gb Lynx HYMP512U64CP8-Y5 AB
512mb Lynx HYMP56U64BP8-C4 AB
Additionally, an Elipida 512mb EBE51AD8AGFA-6E-E pulled from another computer.. I think an HP, as it has an HP sticker with part number on it

Also, all that ram has been tested in another ddr2 computer, and it works.


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## HwyXingFrog

*Re: Dell Optiplex 755; picky with memory*

I was having the exact same issue. I was actually trying to put in 512MB sticks. Then I decided to try 4 1GB sticks and couldn't get it to work.

So, this is what I did:

- Unplug
- Install one of the original 1GB sticks in the top ram slot
- Plug in and wait for it to do it's quick test when it gets power
- Push the power button, then hit F2 right away to get to setup.
- Once in setup, just verify the ram info, then power off with power button.

Repeated the above steps for each stick I installed below:
- original 1GB stick in 3rd RAM slot (from the top)
- new 1GB stick in 2nd RAM slot
- new 1GB stick in 4th RAM slot

Each time, it was able to boot me to the Settings screen (F2), now I am running with a fresh Windows 7 Ultimate 64 Bit install, with 4GB of ram.

Any other feedback you have on your results, let me know.


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## Tyree

*Re: Dell Optiplex 755; picky with memory*

Mixing RAM brands/specs commonly results in problems. 
Also, some Mobo's particularly OEM and other lower quality ones, often do not like having all the RAM slots filled.
For 4GB, the best option is a 2x2GB matched pair, but the Mobo may not except 2GB RAM sticks.


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## HwyXingFrog

*Re: Dell Optiplex 755; picky with memory*

All the ram I was attempting to put in had matched speeds, and each set (of Dual Channel) was a matched pair.

This motherboard was even having issues when I tried putting in a single 512MB stick, it only liked the original ram that was in it before I started messing with it.

After I got Windows 7 Installed, I have now updated the BIOS from Dell's website.

I may try messing with the ram again with the new BIOS and see if it is still picky. I have two other 755's I'm also going to play around with now that I found this Forum post. (I registered on TechSupportForum just for this thread.


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## Tyree

*Re: Dell Optiplex 755; picky with memory*

Even if the RAM has the same speeds, it's different brands and that can cause issues. 
The only thing you can do is try. Crucial is commonly the most compatible brand for OEM Mobo's.


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## HwyXingFrog

*Re: Dell Optiplex 755; picky with memory*

Yeah, but explain why a single 512MB stick of the same brand in there by itself still has issues. Overall, I didn't do as much testing as I should have, I just ruled it out as a bad Motherboard until it magically started working due to a fluke series of events.

When it gets down to it, it is picky and finicky Dell hardware. I will post my findings on the further tests I will probably do later this week on my other two 755's I have in my garage.

If it is this picky, I can see why these old Dells were given to me.


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## wkw427

*Re: Dell Optiplex 755; picky with memory*

Well we got a shipment of memory, some ddr3 for newer pcs, and a bunch of CT25664AA1067 - 2GB, 240-pin DIMM , DDR2 PC2-8500 from Crucial.com for the 755s.. works like a charm


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## Tyree

*Re: Dell Optiplex 755; picky with memory*

Glad you got the issues resolved.
Crucial is always the best brand choice for OEM PC's to help insure compatibility.


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