DDRAM timings and AMD64?

I have an Asus A8N-SLI Deluxe socket 939 motherboard with
two 1GB sticks of OCZ Platinum enhanced latency DDR500 memory.
I am trying to optimise the memory timings at a FSB of 400MHz.

I am reasonably familiar with the standard DDRAM timing options:

CAS# latency (Tcl) 2-3T Use 2.5T
Min RAS# active time (Trcf) 5-15T Use 5T
RAS# to CAS# delay (Twrt) 2-7T Use 3T
Row precharge time (Twr) 2-7T Use 3T

The OCZ web site tells me the settings to use for these.

But there are some new timing options for AMD64 systems, and
I have no idea what the optimum (manufacturer's recommended)
stable settings for these are.

Row cycle time (Trc) 7-22T
Row refresh cycle time (Trfc) 9-24T
Read to write time (Twrt) 1-6T
Write recovery time (Twr) 2-3T
1T/2T memory timing 1-2T

The last of these options has some help text in the BIOS:

"Select DRAM commands and addresses will be driven for
1 clock or 2 clock cycles. 2 clock cycles should only
be set with unbuffered DIMMs"

Am I right in thinking that someone in the Far East, unfamiliar
with English syntax, has written the logic of that statement
backwards? That it should be:

"If you have unbuffered DIMMs, you should use 2T, not 1T."

Trial and error with Memtest86+ v1.65 takes at least an hour
before the computer either crashes or detects a lot of memory
errors. It would take me several days to stumble upon the
optimum timings purely by guesswork.

I'd rather find some memory settings that are stable and
reliable, than push the memory to the limit and have a bit
error every half hour.

Does anyone know what the recommended timings are for good
DDR500 memory running at 400MHz FSB?

I'm in the same boat with my A8N-E and Patriot DDR500 memory.
Try using the NVIDIA tuning software, might help.

Also people at this site (Forum for A8Ns) might have some good advice.
http://asustech.15.forumer.com/

wrote in message
oups.com...
I have an Asus A8N-SLI Deluxe socket 939 motherboard with
two 1GB sticks of OCZ Platinum enhanced latency DDR500 memory.
I am trying to optimise the memory timings at a FSB of 400MHz.

I am reasonably familiar with the standard DDRAM timing options:

CAS# latency (Tcl) 2-3T Use 2.5T
Min RAS# active time (Trcf) 5-15T Use 5T
RAS# to CAS# delay (Twrt) 2-7T Use 3T
Row precharge time (Twr) 2-7T Use 3T

The OCZ web site tells me the settings to use for these.

But there are some new timing options for AMD64 systems, and
I have no idea what the optimum (manufacturer's recommended)
stable settings for these are.

Row cycle time (Trc) 7-22T
Row refresh cycle time (Trfc) 9-24T
Read to write time (Twrt) 1-6T
Write recovery time (Twr) 2-3T
1T/2T memory timing 1-2T

The last of these options has some help text in the BIOS:

"Select DRAM commands and addresses will be driven for
1 clock or 2 clock cycles. 2 clock cycles should only
be set with unbuffered DIMMs"

Am I right in thinking that someone in the Far East, unfamiliar
with English syntax, has written the logic of that statement
backwards? That it should be:

"If you have unbuffered DIMMs, you should use 2T, not 1T."

Trial and error with Memtest86+ v1.65 takes at least an hour
before the computer either crashes or detects a lot of memory
errors. It would take me several days to stumble upon the
optimum timings purely by guesswork.

I'd rather find some memory settings that are stable and
reliable, than push the memory to the limit and have a bit
error every half hour.

Does anyone know what the recommended timings are for good
DDR500 memory running at 400MHz FSB?

Yesterday, I wrote:
I have an Asus A8N-SLI Deluxe socket 939 motherboard with
two 1GB sticks of OCZ Platinum enhanced latency DDR500 memory.
I am trying to optimise the memory timings at a FSB of 400MHz.

I think I've figured it out. At least, I've found settings
that give no errors in a 24 hour Memtest86+ run.

CAS# latency (Tcl) 2-3T Use 2.5T
Min RAS# active time (Trcf) 5-15T Use 5T
RAS# to CAS# delay (Twrt) 2-7T Use 3T
Row precharge time (Twr) 2-7T Use 3T

Row cycle time (Trc) 7-22T
Row refresh cycle time (Trfc) 9-24T

Based on the minimum and maximum permitted values for
these settings, I'd guess that the optimum values a

Either, Trc = Trcf + Twrt
or, Trc = Trcf + Twr

And ordinarily, Trfc = Trc + 2

Read to write time (Twrt) 1-6T

The BIOS default value is 5. Setting it to anything
less than 5 gives memory errors in the modulo-20 test:
(00000000 should be ffffffff, or vice versa.)

Write recovery time (Twr) 2-3T

If 3T is good enough for DDRAM overclocked to 600MHz
(as it must be, or the maximum permitted value would
be higher), then 2T is perfectly good for DDR400.

1T/2T memory timing 1-2T

1T must be the setting for registered memory only.
The computer freezes if 1T is used with unbuffered DIMMs.

Bill wrote:
Is this what you're using?

http://www.ocztechnology.com/products/memory/
ocz_el_ddr_pc_4000_2x1024mb_dual_channel_platinum_ xtc

If so then they will run 3-3-3-8 1T at DDR500 with 2.70 volts which is
higher than the default Auto setting. But since you're only running them
at DDR400, they can probably run 2-2-2-5 timings, but you'll have to up
the VDIMM voltage to 2.80v or 2.85v.

That's the one. I bought the version with the DDR500 timings stored
in the SPD chip, because it was the only OCZ Platinum 2x1GB
memory in stock at the good price I was offered, but I want to run
it at standard DDR400 speeds (not overclocking my CPU).

The SPD chip didn't contain dual settings for DDR400 as well as
DDR500 speeds, so I'm having to look them up on the mfr's web
site, or failing that, guess them.

I happen to know that the recommended timings at DDR400 speeds
for the Gold Enhanced latency DIMMs is 2.5-3-3-5, and the Platinum
EL goes down to 2.5-3-2-5, but when it came to the extra settings
supported bu the AMD64 architecture, I had little choice but to
figure them out by trial and error.

I'm currently running my DIMMs at 2.6 volts, DDR400, 2.5-3-3-5, 2T.
If you say I can get better results by raising the voltage, I might
try that.