The short answer for this is yes, you can. As mentioned above, you can connect the two together, and as long as they are matched, they are going to work properly. If you are looking to buy two new sticks of RAM for your computer, you should look for matched bundles.
Can I use 4GB of RAM instead of 8GB?
IE you can either use the 4GB RAM or the 8GB RAM but not both at the same time. As you can see there are a lot of probabilities here. Now I always buy 2 of the same if I am going to use it in Dual channel mode.. Or 4 of the same if I am needing that much ram since even companies will now sell matched sets of 2 or 4 or 8 RAM sticks.
Can I use 2 8GB memory modules at the same time?
As long as you have 4 available memory slots, yes you can use 2 8GB memory modules and 2 4GB memory modules at the same time. This does ASSUME that both sets of memory are compatible. So if one set is DDR4 and the other is DDR3, then the answer is no. Otherwise, if they are both DDR4, you should be able to use both sets at the same time.
Can I add more RAM to a 12GB laptop?
Yaa sure if your motherboard supports 12gb,sure that both RAM are compatible with one another like same type DDR3,DDR4 Yes you can, with most 7th and 8th generation Intel cpu’s the maximum ram allowed is ddr4 12gb and there are only 2 ram slots available in a laptop, so you either stay with 2x 4gb sticks or a 4gb stick paired to a 8gb stick.
Can I use 8GB of RAM in dual channel mode?
There are chips which are 4GB and 8GB, in dual channel mode this will not work. But you would still get 12GB total only a little slower. Sometimes you will have to swap the RAM slots since the detection has bugs. Like it will only show 4GB instead of the 8GB. Swapping the slots might work..
