Adding more RAM at different speeds? Will it impact performance as much as to make it worse than without adding it?

Question

I got a new laptop with 4GBs of ram, expandable to 8GBs. It has 1 4GB stick DDR3 PC3-12800 at 1600Mhz. I can't seem to find another one exactly the same locally, the closest I've found is 1 4GB stick DDR3 PC3-10600 at 1333Mhz. So my question is, I know they will both run at the slowest speed, so even if I have more available RAM it will become slower. Is the performance loss big enough to make the upgrade not worth the hassle?

Answer 1

If the RAM you buy will be compatible, your laptop will run considerably faster.

I bought my laptop with initially 4GB of RAM 1600 MHz, and added 4 more (same frequency). Those 4GB make a big difference when running several applications. Even with the lower frequency the speed will be increased considerably.

The frequency does not make such a big difference.

Answer 2

If your laptop currently accesses the memory at its maximum speed (800MHz for default for DDR3 PC3-12800) and you add additional memory at a slower maximum speed then:

1. Both SoDIMMs will run at the least common dominator.
2. Benchmarked speed for RAM access will drop
3. Actual OS performance will increase as long as your OS can access all the memory. (E.g. no 32 bit windows and more than 4GB RAM).

Answer 3

I would not make the upgrade. Make sure that the RAM modules have the same cas latency, timings and recommended voltage.

If they don't there is a possibility that your computer won't work at all. Or your computer will just slow down the faster RAM modules to equal the frequency of the slowest.

Here's a posting that may explain a little bit about it. http://www.lifehacker.com.au/2010/07/what-are-the-rules-on-mixing-two-different-types-of-ram/