Please offer some advice about memory speed

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Recently, I had to replace my Micron motherboard with an ASROCK K7VT4A Pro
and transplanted my AMD 1.2 Athlon CPU and 256 Meg of 200Mhz RAM.  It seemed
much slower than it was with the Micron OEM board.

So I replaced the RAM with a 1 GIG PC3200 (DDR400) module.  Under memory,
the ASRock motherboard docs says:

Memory:     2DDR DIMM slots; DDR1 and DDR2
                   PC2100 (DDR266) / PC2700 (DDR333)
                   for 2 DDR DIMM slots, Max. 2GB;
                   PC3200 (DDR400) for 1 DDR DIMM slot, Max. 1GB

However, when I go into the BIOS set up, it shows the memory running at only
Under the Advanced section, Dram Frequency, it only shows two choices:  133
(DDR 266)
and AUTO.  The manual says that I can leave it on AUTO or set it to my
desired frequency.
But the only choices are AUTO and 133Mhz.

What am I missing?

Kraig Whiting

Re: Please offer some advice about memory speed

On Thu, 02 Jun 2005 02:08:45 GMT, "Kraig Whiting"

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Just to clarify, your Athlon 1.2GHz is the 100MHz FSB
version, not the 133MHz FSB version?  There were both types
up until (1.4GHz, IIRC).

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That is the maximum "potential" of the board based on the
KT400 chipset and relative supporting bios options.

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It is correctly functioning because the speed of the chipset
is not at maximum in your case, it is dictated by the spec'd
speed of the CPU.  PLUS, on a socket A Athlon system the
best performance is typically seen by running the memory bus
at same (synchronous to) speed as the FSB.

Therefore, if your Athlon has a 133MHz FSB, AKA DDR266, then
your memory should likewise be at 133MHz clock rate, DDR266,
AKA PC2100 speed.

On the other hand, if your Athlon has 100MHz/DDR200 FSB, the
memory would be at 100MHz clock rate.  In that case it just
"might" be of benefit to raise the memory bus to 133MHz as
an asynchronous +33 setting, because 100MHz memory bus is
awefully slow for a 1GHz + CPU... but you could of course
benchmark your more demanding apps or use popular benchmark
tools to determine which is more appropriate for your uses.

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The options on KT400 were typically either the same speed as
the FSB, or +33 faster... "sometimes" -33 slower, but that
wasn't nearly as common, the whole point of KT400 over KT333
was official support for the AGP bus while FSB was
166MHz/DDR333, and  ability to run memory at "up to" 200MHz
if/when the CPU was within 33Mhz of that.

In other words, to run your PC3200 memory at PC3200 (200Mhz)
speeds, you'd need a CPU that has at least 166MHz FSB.

There ARE other things you can do if you feel up to some
experimentation.  For example, even if you don't want to
overclock the total speed of the CPU, you could reduce it's
multiplier to, perhaps 7X, and raise the FSB to around
172MHz, and then the memory would run at 172MHz or 205MHz
(but again, Athlon socket A systems usually run better at
same memory bus as FSB, so the lower 172MHz would probably
be better than the higher 205MHz, especially considering
that you may be able to run better memory timings.

That's a lot of work for an old Athlon 1.2 though, you could
just leave it alone content that it's running as expected
and if you need more performance then reuse that PC3200
memory with a newer board and CPU... though even an Athlon
XP @ ~ 2.1GHz is a pretty big improvement over the 1.2
Athlon, including the fact that it adds SSE support.

Re: Please offer some advice about memory speed

Thank you for your detailed explanation.  I appreciate your time.

I've purchased an AMD Athlon XP 3000+ Barton 333 MHz FSB with 512 KB L2
cache.  I'll see what I can do with that this weekend.


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