Mixing Ram capacities in different DIMMs and Banks
Good afternoon everyone,
I was curious about something I saw online and I was hoping someone could clarify it for me.
I see that if I mix RAM capacities in my IMAC, for instance keeping the base 4gb in slot 2 and 4 (DiMM 0), and then add 16gb to slot 1 and 3 (DIMM 1), my RAM speed in "System Information" drops from 2667 MHz to 2133 Mhz. But if I mix and match DIM slots, 4gb in slot 1 and 2, and 16gb in slot 3 and 4, then I get the full 2667 MHz showing up in "System Information"
HOWEVER, in practice, it looks online that geek bench tests show that having paired RAM sticks in the same DIMM slot gives twice as much speed as splitting the pairs and having 1 from each pair be both in DIMM 0 and 1.
so I am wondering the following:
- Does the drop from 2667 MHz to 2133 MHz shown in "System Information" when having 2 different capacity RAM sticks, but each paired correctly ACTUALLY give you a drop in performance like it shows?
- if it does drop in performance for using different capacity RAMs, why does it occur if both RAM sticks are 2667 MHz?
- And finally why does "System Information" show the 2667MHz for mismatching the pairs in different DIMM Slots, when in tests this configuration provides half the speed.
From what Im gathering, you get the BEST performance if you only use 2 sticks or 4 sticks of the same capacity. IF you get 2 different capacities, even if you slot the pairs in the same DIMM slot, you will get a reduction in speed. This mixed capacity, but proper pairing in DIMM slots is the second best option, but you get that reduction in speed. and the third and worse option is putting the 1 stick from each pair in both DIMM 0 and 1. Even though "System Information" states its back up to 2667 Mhz, in practice you get a huge reduction in performance for not seating the RAMs in pairs in one DIMM.
