Different RAM Speeds

July 15, 2012 6:31 AM

Can I use slightly slower RAM from my old computer in my new one?

I had a short (1 year) upgrade cycle between my old computer and my new one, due to a disastrous crash.

The new one has a 3.4 Gh i7 CPU and Ivy Bridge support. It has 12 Gb of DDR3 RAM, but I'm not sure of its speed. There's an open memory slot, which I'd like to fill with one of the modules from the old computer. I have a 2 Gb module marked DDR3 1066. Is that the same speed as the new RAM, and if not, will it slow down the machine? How much of a difference in speed is OK? (I'm not overclocking.)

Thanks.

posted by KRS to Computers & Internet (9 answers total)

RAM in a machine always works at the speed of the slowest stick. The new RAM is working at probably a somewhat higher speed, and with 12 GB already in there, 2 more won't make much of a difference unless you are doing high end video editing and such like that
posted by deezil at 7:07 AM on July 15, 2012

As long as the CAS latency is the same, you should be fine. Be noted, though, that your computer will underclock whichever RAM has a higher DIMM, if they're not exactly the same.

I would say, since RAM is pretty cheap, to just pick up an exact copy of what you already have in the new computer to fill that last spot.
posted by erstwhile at 7:08 AM on July 15, 2012

Seconding the above, 1066 is as slow as it gets, but if the current RAM is quite slow then it wouldn't make much difference, but you can't really tell without knowing the specs on the current RAM... Did you pull a stick out and check for a label on it?

(And a brand new 2GB stick matching your current RAM is going to be less than 20$, or a matching 4GB stick is generally less than 25$. Going around with mismatched RAM is like going around with mismatched socks.)
posted by anaelith at 7:15 AM on July 15, 2012

You can download Speccy and run it to find out the speed of the RAM that's in there now. Unless you're an extreme high-end power user the difference between 12 and 14 GB of RAM is not going to be noticeable at all. Were it mine, I would just leave it alone at 12GB, unless the empty slot was ticking my OCD. Then I would just buy a module that matches what you've already got.
posted by laconic skeuomorph at 8:42 AM on July 15, 2012 [1 favorite]

More RAM is good if (a) you're running stuff that uses up so much of it that disk swapping happens and your machine slows down or (b) you're running an OS that can use it effectively for disk caching, and you spend a lot of time doing disk access.

Unless you're doing lots of video editing or working with lots of ridiculously high resolution images for page layout or running a bunch of virtual machines at the same time, 12GB is buckets of RAM (this may not be true in four years, but it's certainly true now). Upping it to 14GB would make almost no difference - except that what you're proposing to do will most likely slow down your entire 12GB array to match the extra 2GB stick, leaving you with slightly less performance than you started with.
posted by flabdablet at 9:27 AM on July 15, 2012 [1 favorite]

DDR3 RAM generally run in matched sets (depending on the configuration, either a set of 3 sticks or a set of 2 sticks). Just because you have one slot free doesn't necessarily mean you can just plug in an extra stick of RAM.

12G is loads and increasing it to 14 isn't going to provide you with any noticeable difference and may negatively affect your performance if your motherboard will even recognize and use the old stick of RAM.
posted by porpoise at 12:35 PM on July 15, 2012

um...Sell it and buy an SSD instead.
posted by Thisispiggy at 1:38 PM on July 15, 2012

If your old RAM would end up doubling your total memory, I'd say go for it, but from 12 GB to 14GB is unlikely to make a huge difference.
posted by Good Brain at 3:28 PM on July 15, 2012

How much of a difference in speed is OK?

While downcycling ram will affect performance, it's hardly every a drastic hit on performance. So I wouldn't focus too much on it as an overall performance factor. Your other bottlenecks will primarily be your HDD, CPU, and video. I think the suggestion to buy a SSD is a good one, as storage is the most commonly overlooked performance hitter. You could have a decked out computer that still takes 30+ seconds to boot due solely to the HDD.

From there it really depends what you intend to do with the computer when looking at performance. Planning on mostly playing games or rendering video? Those types of tasks really benefit from all round good specs. Memory speed would affect performance, but not as much as the GPU, CPU, or HDD. So if spending money, I'd put it into those components first.
posted by samsara at 5:50 AM on July 16, 2012