Dell Optiplex 755 SFF RAM upgrade problem.

[cookie_monster_17]

So I’ve done a lot of searching on this forum about upgrading my PC. So far everything has gone without a hitch. The advise I followed was mostly from this website but now I feel like I can’t find the solution.

My build so far is an Optiplex 755 SFF with a lovely E8600 core 2 duo CPU. A seagate 500GB HDD and (originally) 4GB of Samsung PC2-5300U DDR2 ram in a 4x1 configuration.

I’ve purchased online 4x2GB DDR2 RAM also from Samsung. This time the base clock is upped to 800Mhz.

From my understanding, the clock speed rarely has an effect because of the dynamic way that signals for these devices work? I.e it can essentially de-tune to 667mhz if the system needs it.

The problem that I am having is that when I replaced all the ram at once, it wouldn’t boot and displayed a “3-4” error message on the indicator array on the front panel. This refers to a memory issue. I removed all but one and still the problem persisted. I therefore removed that and placed in a working stick from the old build and included a stick from the new set. When I enter the bios the system can see the 2GB Stick (+ the old 1GB stick)

So my question is, why can the system know that it’s there, but when I install all of them does it not like it?

Have I bought the wrong type of RAM? I heavily researched and they snap into the slots perfectly. I’m pretty sure they’re low density too!

Any advice?

 

[william p]

The low density 2 GB modules should have chips on both sides. An x64 somewhere in the description or part number indicates this also. If it's listed as AMD RAM then it's High density, x128 also. The best way to buy RAM is to get it from Crucial.com. They guarantee their kits to work. Or shop by their part#.
You should have no problem running 800 DDR2 RAM in that. Did you update your BIOS? It's easy to do from Dells website. I'm guessing you did because of the late model CPU. if you would list the part# of the RAM you bought maybe we can figure out the problem.

 

[cookie_monster_17]

Thanks for your reply! I’m presuming it’s low density because chips are on both sides. The sticker on it says “Samsung 2GB DDR800 FG72N”

It seems like a generic sticker

Another one on there says “2GB 800Mhz 256x4”

To go into more detail the chips all say:

Samsung 904 K4TG044QQ-ZCF7

DDR2 EAHD

I will continue researching too. I did update the bios to the A22

The bios event log says “memory size different” and “out of range”

Hope this helps!

 

[william p]

The FG72N concerns me. 72 usually represents ECC RAM. x64 is 8x8, x72 is 9x8 to represent the extra ECC logic chip.
I'm not getting any search results on those Samsung numbers. 256x64 is correst for a low density 2 GB module.
I would look into returning those and try here.
http://www.crucial.com/usa/en/compatible-upgrade-for//optiplex-755-series-%28desktop-mini-tower-and-small-form-factor%29

 

[cookie_monster_17]

Could you share your research so that I may read also?

I can’t seem to find much about the FG7/2N sticker either!

 

[cookie_monster_17]

Here is the original advert:

https://www.ebay.co.uk/itm/8GB-Samsung-4x2GB-DDR2-Memory-PC2-6400-800MHz-desktop-memory-Ram-/253889922766?txnId=2333964721015#vi__app-cvip-panel

 

[william p]

It doesn't look like ECC. It would have a ninth chip in the middle. I'm still not getting a datasheet for that.
From the listing it looks like it should work.
I use Crucial, or Nemix RAM. They both list products specifically for Dell.

 

[cookie_monster_17]

Okay so I’ve taken every stick out and put one at a time. A single 2GB stick prevents the system from posting.

An old functioning 1GB stick paired with a new 2GB will post and the bios will see the 2GB stock and even its clock speed. When I get to the OS (win 7 enterprise 64bit) the system will not see it but the software CPUZ will see it too.

Very confused.

What troubleshooting software side can I do?

I don’t believe they are ECC rated ram sticks as they look identical in almost everyway to the 1GB Samsung sticks that are working.

Head scratching for this one..

 

[Calvin7]

Memory is guaranteed in the form sold. Mixing old and new memory have no guarantee to be compatible together as they have never been tested together. You can do your own compatibility testing with no guarantees.

 

[cookie_monster_17]

Memory is guaranteed in the form sold. Mixing old and new memory have no guarantee to be compatible together as they have never been tested together. You can do your own compatibility testing with no guarantees.

Hmm.. I understand your point, so to speak, but this was a kit which was bought all together. I've scoured these forums to get the details of the RAM which is required for my system and from what I can tell these sticks are compatible yet for some reason they won't work...

 

[cookie_monster_17]

Windows Memory Diagnostics doesn't come up with any results. Not surprising since the 1GB Stick I have in the system (for testing with the new sticks to allow it to boot) is usable so I presume the WMD is only able to test that stick.

What other methods for testing is there? I've seen the program MemTest86+ but I've never used it.

 

[william p]

You might try a CMOS reset to get the old RAM settings cleared out. There should be a jumper for this on the MB. Turn it off, install the new RAM, and reset the CMOS before booting. If you have the correct RAM ( and as far as I can tell you do) it should recognize it.
The instructions I found for this are with the computer off and powered down (unplug it and hold the power button in) remove the password jumper and place it on the RTCRST jumper next to the battery for 5 seconds. Then put it back.

 

[cookie_monster_17]

Okay so I took the CMOS battery out for a few seconds. Didn’t do anything. I know what a jumper is but I don’t know in what circumstances you meant to use it? It’s currently placed atop a point at which the board says Password, so I’m guessing that’s the BIOS password reset. Other than that I’m not sure what you mean mate!

 

[william p]

Removing the battery should do the same thing. There is another "jumper" by the battery. It will just look like 2 pins w/o the jumper installed. Should be labeled RTCRST or something similar. You take the "jumper block" off of the passwor jumper and put it on the RTCRST pins, then put it back.
If that didn't work then I think you may need other RAM modules.

 

[cookie_monster_17]

Nothing... damn. The eBay listing said it was PS2-6400U which I’ve read works fine.
I think I’m going to open an eBay request.
The seller listed as non return but I’m stilling challenging this, I bought it on the assumption his listing was correct, which it can’t be otherwise it would work in my system, right?

 

[william p]

In the Samsung data sheets that I have seen for other modules they list 3 different speed ratings for their RAM. Each has different timings.
My advice is to either buy from vendors that specify Dell compatability, or use their (Crucial) part numbers to shop elsehwere if new isn't an option.
Good luck with Ebay. It seems to me it should work.

 

[cookie_monster_17]

Removing the battery should do the same thing. There is another "jumper" by the battery. It will just look like 2 pins w/o the jumper installed. Should be labeled RTCRST or something similar. You take the "jumper block" off of the passwor jumper and put it on the RTCRST pins, then put it back.
If that didn't work then I think you may need other RAM modules.

I think I might have it! - I work with these optiplexes on a daily basis but only done so for 2/3 months now and today on the test bench I took a couple sticks of RAM that were giving a system a 3-4 error (Memory modules) and performed a full BIOS reset - I disconnected the jumper, took the CMOS battery out then installed the sticks - after booting up... VOILA!

What I need to do now is get home later tonight and see if this test will work with the upgrade to my own system.. fingers crossed!

The problem I was having was that when I was removing the CMOS battery and moving the jumpers around, I wasn't turning the system on. So I would take the small battery out, wait for 30 seconds, put it back in and boot up. It might sound very silly and probably quite obvious but for some reason turning it on without the CMOS didn't seem like the thing to do to me.

I'll update later if it works or not!

 

[cookie_monster_17]

Okay so still nothing...

I took out the cmos and removed the jumper from the password point. Replaced the RAM in all forms, either with the old or not, still nothing.

It’s seen by the BIOS and it says unbuffered but still nothing


Guess I’m done...