I've got a Gigabyte GA-Z77X-D3H mobo with 4 DDR3 dual-channel memory slots.
I'm currently running 8 GB of DDR3 1600 (Kingston HyperX, 4gb x 2) paired in slots 1 and 2 with 3 & 4 empty.
I have 4 GB of DDR3 1333 (G. Skill NS, 2gb x 2) sitting around I was thinking of adding. Would running the 1333 paired in 3 & 4 be fine with the 1600 in the other slots since this is dual-channel, or do I need to keep size/frequency consistent in all four slots?
Also, would I need to clock the 8GB of 1600 down to 1333 if I added the additional memory? If so, would this mean keeping the current 8 at 1600 would be better than adding 4 and lowering the frequency?
If you install the 1333mhz ram with the 1600mhz ram then they will all run at the slower speed. 8gb of ram is sufficient for most applications and all gaming and with gaming even if you add the ram the computer will only use what it needs and there are no games that require more than 6gb of ram.
Is there a reason why you need to add the extra ram? Are you doing any video editing or video rendering with 3D graphics.