Non-matching RAM sticks.

Intel Celeron 2.80 ghz processor
September 21, 2010 at 16:04:40
Specs: Windows XP SP2, Intel Pentium 4 2.6Ghz
Hi, just a quick question. I have this old computer and I just need to help it run a bit faster.

I have 512MB of DDR2 533MHz (PC2-4300) installed. I want to buy a 1GB of DDR2 667MHz (PC2-5300). Would the 1GB memory stick be down-clocked to 533MHz? If so should I just take the 512MB stick out, or do the benefits of getting all the memory down-clocked outweigh taking the 512MB out?

Also do they have to be the same brand? And finally do they have to match i.e. same memory stick size or will it be ok with the 1GB and 512Mb together.


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September 21, 2010 at 17:38:30
A little tough to say since you didn't bother listing your motherboard or CPU. You listed a P4 at 2.6GHz & a Celeron at 2.8GHz...which is it?

- if you mix DDR533 & DDR667, they will both run as DDR533.
- if your CPU runs at 400MHz FSB, the optimal RAM speed is 266MHz (133MHz actual).
- if your CPU runs at 533MHz FSB, the optimal RAM speed is 333MHz (166MHz actual).
- if your CPU runs at 800MHz FSB, the optimal RAM speed is 533MHz (266MHz actual).
- if your board supports dual channel mode & has more than 2 RAM slots, you need to choose the correct 2 slots for dual channel to be enabled. But because of the differing RAM, it may not run in dual mode.
- 1.5GB is better than 1GB.

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September 23, 2010 at 16:26:38
It's a Celeron 2.8GHz. The CPU runs at 533MHz FSB. There is only 2 RAM slots.

What determines the optimal RAM speed for a specific FSB speed. I read that RAM speed should typically be double to that of the FSB, in my case actual RAM speed runs at 266MHz and my FSB is at 133MHz?

I think I will buy PC2-5300 memory, not sure if this will run on dual or single mode.

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