Seeing how the memory only runs at 400 MHz when there are two DIMM's,
has anyone had any experience or benchmarks on which two slots it runs
best in?
The manual states that DDR can run at 400 MHz in either slots 1&2 or
1&3.
I can only tell which slot is #2 as it is in the middle. I don't know
which is 1 and which is 3.
Presently I'm running slots 1 & 3 but wondered if there was any
difference otherwise.
Thanks,
Dim-Ize
The AMD processor drives the memory in the Athlon64 world. The S754
socket processor has two address busses. One is connected to Slot 1
(nearest the processor), and the second address bus goes to
Slot 2 and Slot 3. To balance the currents in the busses, the
address busses are the 1's complement of one another, but
only the bus with active control signals on it is actually
using the address info.
In any case, with two address busses, there is hardly any
difference between using Slot1 & 2 versus Slot 1 & 3. Assuming
the majority of bus terminators are near slot 3, I would
personally choose 1 & 3, without doing any further research.
The most demanding part of the memory bus is the address.
This is because all the memory chips on the DIMMs, (32 or
48 of them, for two or three double sided DIMMs), are loading
the bus at the same time. The data signals, on the other hand,
are only one load per bank, or six loads for three double
sided DIMMs.
In terms of absolute best design, the A7N8X Nforce2 has
three address busses. That means every slot has its own
private address bus, and is the reason that board can run
three sticks at DDR400.
In terms of the difference it makes, picking good slots
helps if you are overclocking the memory bus. When running
at stock speed, picking good slots means having a low error
rate on the memory bus (effectively zero, but it can never
be exactly zero).
HTH,
Paul
