6 GB of mixed-speed RAM better or worse than 4 GB of matched pair faster RAM?

December 26, 2009 8:55 AM

I just picked up 4 GB of DDR2 800 RAM to upgrade my computer. It already has 2 GB of DDR2 533. Should I get rid of the old RAM and just use the new, or should I install all of it?

Santa was good to me this year and I received two 2 GB sticks of DDR2 800 of RAM for Christmas. My current desktop already has two 1 GB sticks of DDR2 533 RAM. My motherboard has 4 slots for RAM and I'm running Win 7 x64, so if I'm not mistaken I could actually install the new sticks in addition to the old ones and have 6 GB of RAM total.

However, I seem to remember something about how installing faster RAM in addition to slower RAM will slow all of the memory down. Will this drag on my system performance? If so, would the trade-off be worth installing all 6 gigs anyway?

posted by suburbanrobot to computers & internet (7 answers total)

Assuming your computer will accept all the memory at once, and your computer is capable of using the memory at the higher speed of the new sticks, ask yourself this question: which do you value more, overall capacity or overall speed? If you're a gamer, probably the latter, otherwise the former will probably give you more of a benefit, but only you know for sure.
posted by davejay at 9:02 AM on December 26, 2009 [1 favorite]

I asked a similar question a few months ago (and you've just reminded me to go back and mark best answers). All the numbers in my question are lower, but the answers should still be helpful.
posted by Partial Law at 9:15 AM on December 26, 2009

Your memory is correct-- the memory will all run at the lower speed. Personally, I would take out the older sticks, not just because I would rather have the new ram unimpeded, but because 4 gigs is plenty and ram likes to be set up in identical sticks-- so having 2 x 2 is a boon, rather than 2 x 2 + 2 x 1. However, there's no real reason you couldn't experiment with both the 4 gigs and the 6 gigs, and do some time tests on certain things to see which you prefer/feels faster.
posted by stresstwig at 9:17 AM on December 26, 2009

You need to know what your northbridge/memory controller is, and how's using the memory, before you know whether you can even use DDR2-800 at 800 speeds... If your motherboard's max speed is 533 and you mix the two together there should be no problem, the 800 will run at the slower speed. If you replace all of it with the 800 it will work at whatever is the fastest speed your motherboard is capable of.
posted by thewalrus at 9:29 AM on December 26, 2009

since you're on 64-bit Windows, and (I assume) your motherboard supports the 6GB configuration, you might as well do the 6GB configuration.. it'll slow the 800MHz RAM down, but, depending on your processor and chipset, there might be a reason why the existing RAM is 533MHz, so it might run at 533MHz regardless of having the original RAM in or not. really, unless you're running really performance-critical stuff, the difference isn't going to be noticeable (not to human eyes, at any rate - your computer is slowed down much more by your spinning-magnetic-disk hard drive than it would be the RAM).
posted by mrg at 10:43 AM on December 26, 2009

Put all the memory in.

The drop in speed from your memory configuration will pale into insignificance from the benefit that the additional memory will give you. As mrg noted, the bottleneck will be your hard drive, not the memory.

If you're a hard core gamer then you'd be better off upgrading your graphics card and increasing the memory rather than trying to boost the what you already have.
posted by mr_silver at 11:04 AM on December 26, 2009 [1 favorite]

If your use is ram heavy (video/photo editing, lots of gaming, etc) then you should put it all in there. If your use is never this heavy then I would go with the faster ram. No use getting a performance hit for ram you never access.

You can see your ram usage with task manager. Put in the 4gigs and see if you ever come close to exhausting all of it.
posted by damn dirty ape at 12:48 PM on December 26, 2009