Chosen Solution
I want to upgrade the memory to 8gb. I could buy two 2gb cards for the extra slots, but is it OK to fit a 4gb card to one slot? I’m thinking that I can add another 4gb later if I need to.
RAM Type: PC3-8500 DDR3 Min. RAM Speed: 1066 MHz Details: Supports 1066 MHz PC3-8500 DDR3 SO-DIMMs (204-pin). Standard RAM: 4 GB Maximum RAM: 16 GB Details: By default, 4 GB of RAM was installed as two 2 GB SO-DIMM modules. Two slots free. Andy is somewhat correct is is referring to interleaving and is preferred but not as essential as it once was.
Buying the single 4 GB is the way for exactly the reason you said, it leaves a slot to add more RAM again down the road. But, remember that if you add a second 4 GB stick later it should exactly the same as the first. Pairs of RAM should always be identical.
With RAM prices right now, it is sometimes cost-prohibitive for certain PC builds to contain kits of two sticks. This especially impacts the budget audience. A lot of forums online – and I was guilty of this up until about a year ago – will strongly urge PC builders to strictly use RAM modules in multiples of two. This is to enable dual-channel platform capabilities, which will utilize 2x64-bit channels on the memory bus (128 data traces on the motherboard going to the IMC) instead of one. This effectively allows our memory to double its maximum theoretical bandwidth by working in parallel, since each stick can only push 64 bits of data at any time.
