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I have a DDR3-1333 to replace, am I sure that any DDR3 equal or faster than 1333 is suitable?

Tobia
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1 Answers1

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Yes, you can be 99% sure. I don't say 100% only because there are always surprises.

Memory chips have a specification, a data sheet, what says their maximal, but also their minimal clock rate. Obviously the maximal is important, but also the minimal exists.

The background: Memory chips used today in PCs are DRAMs. They are effectively an array of microscopic capacitors. 1 capacitor = 1 bit. If they are loaded, we have a bit 1. If not, we have a bit 0. (Or the opposite, it does not matter here.)

These capacitors slowly dissipate their charge, causing the chip to slowly zero itself out. If the CPU (more clearly, the memory controller which is either integrated into the CPU or into the motherboard) reads their content out, even this is a destructive read, and zeroes out their content.

Thus, the memory controllers (chips dealing with your DDR rams) do these:

  1. If you read out some content from a DDR chip, zeroing it, then they write it back into.
  2. They also periodically read out the chip and write them back, to avoid the content loss due to dissipation.

This all happen from the hardware, in the background, from the view of the CPU we can see a stable RAM where we can read and write.

If a DDR chip is driven too slowly, the timing of these background tasks happen too slowly, resulting content loss. However, the dissipation is far slower than the clockrate of the chip, and the clockrate of the chips passing the same RAM socket does not vary so greatly. For example, you can find DDR3 chips maybe between 1GHz and 2GHz, but not for 10MHz and 10GHz. A 10GHz DDR3 memory would probably not work if you drive it with 1GHz, but no such chip exists.

peterh
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