Scotter wrote:
> Hey I'm pretty sure I'm going to buy this motherboard.
> I am trying to decide which RAM to get for it.
> So far I'm pretty sure a safe bet is two chips of 512mb Corsair XMS PC3200
> registered, low-latency RAM.
Make sure it is registered ECC, not simply registered.
One thing I'm seeing out there is PC3500 and
> 3700 and even 4000 running at 500 mhz. I assume this motherboard won't
> support anything higher than PC3200?
It is not the motherboard that determines the DDR speeds that
are supported, it is the processor. All of the AMD64 products
have a memory controller built into the CPU, and that built-in
memory controller determines what DDR speeds are supported.
All of the AMD64 products (Athlon64, AthlonFX, Opteron) support
100 MHz, 133 MHz and 166 MHz DDR. (PC1600, PC2100, and PC2700
respectively.)
To the best of my knowledge, all of the AthlonFX's and Athlon64s
support 200 MHz DDR (PC3200). Opterons do not unless they are
stepping C0 or later. The Athlon64s also do not require ECC.
It is technically possible to use an external memory controller
with the AMD64 processors, and hence use DIMMs at speeds above 200 MHz.
However, no one has done it yet because that would mean throwing
away the tremendous latency reduction you get by using the CPU's
built-in memory controller.
> Thanks for any advice you can give. Also any other advice about this
> motherboard would be appreciated. Since it is so new I doubt many of you
> have it yet... Just today it came up for sale at www.newegg.com
>
One thing to keep in mind about the memory controller built into
the AMD64 products is that they require the CPU speed to be an
in integral multiple of the RAM speed. If necessary, the RAM is
underclocked to create that integral-multiple relationship.
The memory speed table on page 14 of
http://www.amd.com/us-en/assets/cont...docs/23932.pdf
is worthwhile reading for anyone contemplating processor and RAM purchases
for a new Opteron, AthlonFX or Athlon64 system.
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