Combining Two Sticks of RAM (Different Size)

The reason for the recommendation (to do matched pairs) is to avoid common RAM problems. This does not mean you have to have a problem if you don't. It just increases your chances.

It is less of a concern that the RAM modules are of different sizes (2GB vs 4GB).

It is more of a concern when the modules are different speeds (PC3-8500 1066MHz -vs- PC3-10700 1333MHz). Although the system will just run both sticks at the slower speed (1066MHz).

But the real risk (of RAM errors) comes when you run RAM modules with different timings (7-7-7-27 -vs- 9-9-9-24).

But so far so good? Maybe you got lucky. Some RAM will play nice together.

Have you run a RAM test yet? I suggest at least 3 passes with Memtest86+ - Advanced Memory Diagnostic Tool

TheDeerDude said:

Thank you for all this information, it will come in handy in future.
I was aware that the faster stick would be slown down by the other one, but it doesn't matter since it's the one giving me those 2 extra GB and it's still fast.

Now, how are the timings different from the speed?

And yes, so far so good (managed to even play a game which ran more smoothly) but I'll give Memtest86+ a go, thank you.

Here is a good article explaining it. Memory timings - Wikipedia, the free encyclopedia also to see your current timings with your mixed sticks use the memory tab in cpu-z vs spd tab. In your memory tab it should say your single and no longer dual channel since your sticks are different and it has to mix their timings so both are same(ie, one lower).