I have a Dell Optiplex 745 with 4 Gig RAM, 4-1 Gig sticks. I want to upgrade to 8 Gig.
Question: Can I use 2-1 Gig sticks and 3-2 Gig sticks or do I have to use 4-2 Gig sticks?
(It has 4 RAM slots)
Thanks for any help.
Given that you have 4 slots, I’ll go out on a limb and say that you can’t use 5 DIMMs (2 ones and 3 twos.) You need to go with the 4 twos.
I had the same reaction.
I think that “4-1 gig stick” is his way of saying 4 gigs on 1 stick. Which is exactly the opposite to what everybody would assume that ambiguous syntax means.
AFAIK there aren’t 3GB sticks. Which he assumes he can get two of, plus a 2-gig stick he can get one of. Thereby leaving a slot free for further expansion. Perhaps with a 7GB stick since everything’s better with prime numbers. 
Play it safe, and stick with the compatible memory types listed here.
ETA: But whatever you do, don’t buy any 800mhz 2gb sticks.
Funnily enough I have a Dell Optiplex 755 - not the same but near enough - and was faced with the same question. I had to have four 2 GB DIMMS. I later learned that it would take 4 GB DIMMs but my use case wouldn’t see more than 8 GB anyway.
According to the tech spec PDF I linked, the OP’s system takes only 512 MB, 1 GB, or 2 GB (and does mention that you can’t use 800 MHz 2 GBs.)
You may be misreading it. What I’ve read indicates that 2 GB DIMMs were not available at the time.
Here’s someone with four 2 GB DIMMs installed:
And here:
Remember you’ll also need to be using a 64-bit version of Windows to use more than 4gb of ram.
(If you run windows at all, of course.)
If you can even use 4 GB on a 32-bit OS. I still use Windows XP on my home machine (it is a “pry it from my cold, dead hands” situation) and it uses only 2.5 GB of my 4 GB. (I attempted to upgrade to the 64 bit version once, but I was getting hardware compatibility problems and decided to leave well enough alone.)
If you want to upgrade to 8GB of ram you with have to use 4 2 GB sticks of DDR2 RAM as previous linked on voltaire’s post. That said, if you want your PC to use ram more efficiently it is recommended you use the same brands in pairs or all together. You don’t have to do this mind you, but it just makes the memory work faster.
That’s for the different “SFF” (small form factor) model, though your second example doesn’t specify which model they had.
Funny, I’d never have pegged you for a raging Luddite from your other posts. Who knew?? 
:smack::smack::smack:
My only excuse is I was on my sixth beer when I asked…