I recently purchased a DDR 1024 MB 266mhz memory stick. I meant to get the DDR 1024 MB 400mhz stick. Is there a major difference in performance between a 1024-266 and a 1024-400 memory stick?

Thanks What's in the machine now and what will the MBoard support speed wise ? ?
Travel to Crucial.com to find out...It has a DDR 256 400mhz. I am not sure what the motherboard supports, but I know it will handle 2048MB, 1 gig per slotThe point is if the RAM is backwards compatible but the MBoard only supports the lower speed that is the speed the RAM will run at... It has a DDR 256 400mhz. < What size stick 256k, 512k or a 1# gig stick ? Obviously it is running/working at the 400 mhz speed, more than likely the mobo will handle the backward incapability but; it will run the ram at the lower speed 256 ...I would make the effort to get the Right* stick of 400 . Depending on the other size stick, you would want to run this in dual (2 of the same sticks) channel mode.I know the motherboard supports the higher speed because it CAME with it.
I have already installed the 1024mb-266mhz and it works just fine.
I was just WANTING to know how much of a performance difference there would be b/w the 266 & the 400. If it makes a highly noticeable performance increase, then I am going to return it and get the 400mhz stick.
If it isn't much of a difference, then I'll just keep what I have.
Either option, it sure is an upgrade from a mere 256 megs of RAM!!As others have already said, your RAM is now going to run at 266mhz. Now that you have 1280mb RAM(assuming you have th 1g and the 256mb installed, that's a lot of RAM compared to what you're used to. That's also too much POTENTIAL speed being held back due to a mistake. If I were you I would return the RAM while you still can.