Will 3 x 1GB work?

I am finally upgrading my Dimension 4700 from it's original 512MB Ram!

After reading several post, I realized that it would be pointless to upgrade to the motherboard max of 4GB because I am only running the 32-bit version OS. From what I understand, my pc would only recognize 3GB.

Here is the question:

I am looking at purchasing
Kingston
Model KVR667D2N5K2/2G
Type 240-Pin DDR2 SDRAM
Capacity 2GB (2 x 1GB)
Speed DDR2 667 (PC2 5300)
Cas Latency 5

AND

Kingston
Model KVR667D2N5/1G
Type 240-Pin DDR2 SDRAM
Capacity 1GB
Speed DDR2 667 (PC2 5300)
Cas Latency 5

to total 3GB. Will these work together even though the former is a matched set and the latter is not? Is it ok to leave one memory slot unused?

As I'm sure you've noticed, I am new to the "do it yourself" upgrading. Any help would be greatly appreciated.

The 32 bit cap of 3gb is after all system resources are reserved, using 4gb of memory. A 32 bit system can only address 4gb of memory at max, which is then shared between all resources. If your video card has onboard memory (it does), that is also taken away from the total amount of Ram you can have. With a video card of 1gb of ram, that limits the total Ram to 3gb, then the system takes a little more away, leaving your system showing a little less than 3gb. With a video card of 512MB of ram, that means you would cap off at 3.5gb.

With that said, it would still probably just be cheaper to get a 2x 2gb kit and get the whole 4 gb

Patriot Viper 2x2GB kit

Edit: just realized you were looking at 667mhz memory

Kingston 2x2GB kit ~40$

Edit2: To clearify, with a video card using with 512mb of Ram would leave your max Ram at 3.5GB, making 512MB wasted, but its still cheaper then getting a bunch of smaller sticks.

And to answer your original question, you would need to check your mother board for specifications to see if 3 1gb sticks would work, but generally, no. Also, a configuration of 2x1GB sticks and 2x512MB sticks also works on most motherboards.

To add a bit to mr_bojangles' post, using three dimms will put your machine back into ddr mode, eliminating the benefits of ddr2. Two or four modules would be preferable, as then you would keep the inter-leaving benefits of ddr2. Will it matter much? Not really, unless you are doing a fairly large overclock, but it will matter some even at stock settings. Also, some MB's have an issue using all four DIMM slots without a bios upgrade, so 2x2GB is probably your best bet. Even then you may need to change your voltage to get your RAM running properly.

Also, just to complicate matters, you need to put your RAM into the same bank of DIMM slots. Many MB's will have the banks color coded, but you may need to read your MB manual to be sure.

And there was no DDR ram, right? I thought I was fairly clear on the OP's options, including the performance hit of using DDR mode vs. DDR2 mode, without writing a tome of various memory specs.

Who said anything about no DDR RAM?

There is no such thing as DDR mode or DDR2 mode. Just single channel or dual channel. Which can apply to DDR, DDR2 or DDR3.

I know about the differences between the different types of RAM.

Why don't you just post what JEDEC says about DDR mode for DDR2.

Thanks for all the info peoples! To Newegg I go!