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Can I mix and match RAM I add to my system?


I just purchased 1 gigabyte of RAM for my computer and it works great. What
didn’t work was trying to use my previous 2 256MB ram sticks in combination
with my new 1GB Stick. Is there any way to make this combo work? Perhaps a
specific order to install the RAM?

The short answer is: maybe.

On some computers you can, and on others you cannot. On some you can, if as
you suggest, you do it “the right way”. So how do you tell?

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It really all depends on how the computer’s motherboard is designed. The
definitive answer comes from your computer manufacturer. My first step is
always to visit the support web site for that specific computer and see what’s
available, and how memory can be configured.

“The ‘problem’ is simply that different computer
motherboards can accept memory in different, but specific, combinations.”

Another good resource is I’ve purchased memory from them a time or two, and
they have a fairly helpful compatibility identifier which can step you through
the process of selecting the proper memory for your computer.

The “problem” is simply that different computer motherboards can accept
memory in different, but specific, combinations. Some examples:

  • Some require that all memory sticks in the computer be identical. So if you
    have four slots, you can have 4x256meg, or 4x1gig, but you can’t mix the 256meg
    and 1gig sticks.

  • Some allow you to mix, but you must mix in pairs. Meaning you might be able
    to have 2x1gig and 2x256meg.

  • Some require that if you mix, you must do so in a certain sequence. So you
    might be able to put 1gig in slot 1, and 256meg in slot 2, but not the other
    way around.

  • Many require that if you mix (according to whatever other rules there might
    be), the memory sticks share certain other characteristics, such as speed or

As you can see it’s not a simple yes you can, or no you cannot. It really
does depend on the machine you’re dealing with.

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5 comments on “Can I mix and match RAM I add to my system?”

  1. Some more… If I’m not wrong, there’s nowadays, some card to extend capability ram memory, using board slots. Think the problems is, how much memory can I add? It depends of board used! Am I wrong? Tks. Vic-Lxa-PT –

  2. Whether or not your motherboard explicitly requires you match speed and latency on memory sticks, even if they’re different capacities, match them anyway.

    There are three things where seeking bargains can lead to long-term regret… Doctors, shoes, and RAM.

  3. It really depends on the speed when it comes right down to it. If you using 1 stick of 128 with a speed of 100mhz…you can “trick” your sytem by putting in another stick of 128 to increase your memory with another speed, such as 133mhz, but you have to put the faster stick into DIM2 verses DIM 1…and your system will “think” it’s all running at the slower speed. The reverse is not true thou. Always put the faster speed in the second slot, and it whould be fine. Not always, depending on the MB, but I have found sucess in doing that.

  4. I have a Dell Dimension E520 with Vista 32, which has a maximum RAM addressability of 3.1G as I am told by Dell and Crucial. Had 1G in each of the #1 and #3 slots and a 2G stick (also a different speed) in the #2 slot. Worked well for awhile but now it’s acting like it’s running on 500K total RAM. Crucial says each of the 4 slots can only have 1G apiece. Dell is not sure (thanks, guys). I’m going to try that. I suspect the matching issue is a factor here, so double-check with the manufacturer if that’s required.

  5. SIR,


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