On a system that normally uses DDR 400 RAM, would DDR 500 be more
easily overclockable, like just by increasing FSB speed?

The FSB speed is usually 200, but my CPU can handle significantly
greater. The RAM is being upgraded and I want memory that is more
able to handle an increase in FSB speed. Looks like the latency on
the DDR 500 is greater than DDR 400, but will it be able to more
easily handle an increase in FSB speed, up from 200 MHz?

I hope my question is clear enough.

-Judd

"Judd" <jdj (AT) merry-go-round (DOT) com> wrote

It would help to know what motherboard you have, and what
memory brands you're considering. All else being equal, DDR
500 is more overclockable than DDR 400, but there are a few
other considerations... E.g. some DDR500 can run at 250FSB
only at higher voltages, 3.1-3.3V or higher. While some
motherboards, e.g. Intel 865/875-based can't provide more
than 2.8V.

Don't worry too much about latencies, you'll usually get better
performance with a higher FSB regardless of timings. Although
most AMD cpus take better advantage of lower latencies than
Intel chips.

Judd wrote:
But that is what memory dividers are for. A 875/865 offers
1:1, 5:4, and 3:2, and maybe others I don't know about.
If you lift the FSB, then 5:4 can keep DDR400 happy for
a bit, and if you really overclock a lot higher, then
the 3:2 divider can be used to stay within the bounds
of DDR400.

Athlon64 has similar options, and a three bit field in a
memory control register, allows setting an objective target
for memory speed. That too allows compensating for a
raised CPU clock. If you increase the CPU clock from
200 to 240, then selecting "DDR333" instead of "DDR400"
for the memory, helps keep the memory speed within spec.

The main advantage of a DDR500 memory, is running it at the
full rate, to gain a bit of performance from the increased
memory bandwidth. That may required loose timing and
increased voltage. But the most gains come from the CPU and
not the memory, so spending a lot of money on memory, is
only for those with deep pockets. The recent price drops in
processors allows you to get a lot more for your money on
the CPU end.

On the computer I'm typing this on, my DDR400 rated memory
is running at DDR460. Some memories have more headroom than
others, and this stuff will almost reach DDR500. Too bad
my motherboard prevents me from overclocking that high.

Paul