4 ram slots vs 2 - List of Motherboards with 8 RAM Slots 888 dragons slot review

1 and 3 ram slots are physically closer, why does 2 and 4 offer a bit more performance? ... I think the traces still have equal distance and 2 and 4 gives more compatibility with big air coolers if only 2 slots are occupied?

so my task manager said 1 of 2 ram slots used, when i hover it saidslot 1: emptyslot 2: 4,0GB, 1600mhzbut it show 8gb of ram just finemy bro's laptop have both slot used and it said 2 of 4 slot usedis.

Expansion slots: 2 DIMM slots, PCIe x1: 2 Slot, PCIe x16 (Graphics): ... Dell Inspiron 3847, Intel Core i5-4440 3.30 GHz, Ram 4 GB, HDD ...