12 GB of RAM (8+4) at 2400 MHz or 4 GB (4x1) at 3200 MHz
12 GB of RAM (8+4) at 2400 MHz or 4 GB (4x1) at 3200 MHz
It's better to have similar sizes rather than varying ones, as it usually speeds things up. I’m not sure about the current setup, but in the past, unequal sizes meant you’d get full speed for the first 4GB on both sticks (like 8GB total), then drop to single-channel for the remaining 4GB. I usually suggest buying a matching pair, but on a Pentium chip you probably won’t notice any difference.