Mixing different sizes of RAM

I am shopping for a desktop, and am finding some very interesting combinations of slots and RAM sizes (such as 1 gig, 2 gigs, etc.)--all of which is to say, that if I buy one of these desktops, and hten 2-3 years down the road opt for a 4 gig stick, it will be balanced by the original 2 gig stick; or if there are 2 1-gig sticks in the 2 slots, and I insert a 2-gig stick, I will then have a 1-gig and a 2-gig stick.

I have read numerous times that this is not optimal. Is this true?

Even if it is true, will mixing up 2 different sizes slow my computer down? Or just take some of the marginal benefit away from upgrading the RAM? Or take away most of the benefit?

Can someone explain in plain terms what the problem with mixing is?

EDIT: In other words, the reason I'm asking is that if I CAN'T mix a 2 gig and a 4-gig stick, I'll problably have to pay more when upgrading, and get two sticks (of the same size), instead of mixing two different sizes. If there will be this additional expense I'd rather know about it ahead of time.

 

Hi Paul,

See my system specs, that computer was bought brand new less than a week ago with no amendments, that should answer your question. However I wouldn't recommend mixing manufacturers or speed but withought knowing which kind of setup you're looking at it's unlikely we could help further.

 

OK Thanks. HOnestly I'm not sure yet (about manufacturers or speed, ect., as I'm still shopping), but I was just wondering if running a 1 Gb next to a 2 Gb, or a 4 Gb next to a 2 Gb, would be ok. Yes from your system specs that is exactly what I'm talking about. Thanks.

 

For your own piece of mind I would look at, check from the specs what Motherboard is in the system that you would likely be buying, and download the Manual from the corresponding Website and check out the recommendation for Ram from there.

 

Yes the motherboard manual will tell you how it utilises the RAM, like if it will "optimise" the usage by having matched pairs of modules (you will see them sold as kits, like 2 X 1GB or 2 X 2GB).

Different brands and even models of RAM may not work together.