Looking for memory? Too many choices

[jonnyb]

I need desktop memory for my Optiplex 755.
PC2-5300 also called non-ECC, Un-registered, low density and un-buffered.

I see all this memory on Ebay and usually get the wrong memory.

What do all these terms mean? I have done some research and think I got some of it right? What do others say about these letters.

PC2-5300F --????
PC2-5300S means So-Dimm I think
P usually stands for Parity or ECC I think
U would be unbuffered for Desktops I think.
R = Registered - servers I think
F = Fully buffered - servers I think
FB = Fully Buffered I think

Am I getting it right or what?

[Train]

What crucial says.
http://www.crucial.com/store/listpar...tor%29&Cat=RAM

[jonnyb]

I know what they said as I have been there but right now my Optiplexs have PC2-6400 in them which is not listed on any website for this model. It runs fine though. Can I mix a lower number like 4200, 5300 or 5400 with this 6400? Anyone know?

[jdc2000]

Perssonally, I wouldn't try it. At work I have an Optiplex 760 and it is slow enough without using slower memory. Plus, Dells can be finicky about what memory they will use. Possible outcomes in order of likelihood for using other memory:

1. Won't work at all.
2. Boots up but you get all kinds of flaky errors. Very frustrating.
3. Works OK, but slower than with just the 6400 memory.
4. Works OK, no better, no worse.
5.. Works better.

[Train]

6400 is what Crucial does list for it.
Maximum Memory: 8GB
Slots: 4

The Optiplex 745 bunch I have worked on, with 4 GB of ram per computer, are winners in my book Clean installed Win 7 64 bit.

[SpywareDr]

Crucial's recommended RAM is guaranteed-compatible. If it doesn't work, they will fix the problem.

[jonnyb]

I just got a letter from Crucial. Here it is:

Thank you for contacting Crucial. We have two different Optiplex 755, OptiPlex 755 Series (Desktop Mini-Tower and Small Form Factor). That system takes DDR2 PC2-6400, DDR2 PC2-8500, DDR2 PC2-5300, has four slots, and the maximum memory is 8GB. OptiPlex 755 Series (Ultra Small Form Factor) only takes DDR2 PC2-5300, has two slots, and the maximum memory is 4GB. I listed both links below for the two different systems. Also when you mix two different speeds in one system, it will clock down too the slower speed that is installed the system.

From me. See I did not see the 8500 listed on their website. Anyhow, I will now order some more memory.

[SpywareDr]

It's a heck of a lot easier to use the computer needing the upgrade to go to Crucial.com and click System Scanner.

[jonnyb]

I need memory for computers that I have not even purchased yet though. Just doing the research first.

[SpywareDr]

Got it.

[jonnyb]

Got it.

Thanks SDoc though. I am keeping good notes on memory. People on Ebay are selling server memory and don't know what they are selling. Most of my DDR ram has the U on the end of the number like 6400U

[SpywareDr]

U = unbuffered/non-registered