Memory Timings in BIOS

[bloodandsoil]

RAM: Crucial Ballistix PC2-6400, 4-4-4-12, 2.2V
Motherboard: Asus P5B-Deluxe
CPU: Core 2 Duo E6600 2.4 GHz

In my BIOS, when I switch SPD from Auto to Manual, here are the values presented:

DRAM CAS# Latency = 5
DRAM RAS# to CAS# Delay = 6 DRAM Clocks
DRAM RAS# Precharge = 6 DRAM Clocks
DRAM RAS# Activate to Precharge = 15 DRAM Clocks
DRAM Write Recovery Time = 6 DRAM Clocks
DRAM TRFC = 42 DRAM Clocks
DRAM TRRD = 10
Rank Write to Read Delay = 10
Read to Precharge Delay = 11
Write to Precharge Delay = 10

I learned on another forum that I should set the first four settings in order to 4, 4, 4, 12. Like this:

DRAM CAS# Latency = 4
DRAM RAS# to CAS# Delay = 4 DRAM Clocks
DRAM RAS# Precharge = 4 DRAM Clocks
DRAM RAS# Activate to Precharge = 12 DRAM Clocks


But that leaves the remaining 6 settings and I don't know what to set them to. Anyone know? Thanks.

 

[RonAKA]

At 2.4 GHz you don't seem to be overclocking. That begs the question why you would want to switch from SPD to Maunual? Also I see you show 2.2V on the DRAM. Again, why if you are not overclocking?

Suggest you leave DRAM volts on auto, and SPD as well. Download CPU-Z and look at the Memory tab which will show you what you are actually running. My guess is that it is already 4-4-4-12, and all the other settings will be fine.

Not sure what your objective is?

 

[n7]

The last six subtimings you can basically tighten till you see instability.

I haven't tested them with anything other than my Micron D9GMH, but you can usually do around

x-x-x-x-4-30-5-10-7-12 with no issues, & with slightly better performance than the default x-x-x-x-6-42-10-10-10-10.

You'll find that you likely tighten them even more than that, but keep in mind that can prevent as high overclocking.

I found the first two subtimings didn't do all that much for performance, but the last four certainly did for SuperPI.

 

[Lemon law]

To RonAKA,

At least in my case there was a compelling reason to switch from SPD to manual. I had two sticks of mixed PC3200 dram, but somehow SPD decided to run them at less than PC2100 speeds. And playing with manual settings yielded a 50% memory throughput increase at zero overclocking in my case.

In a better case scenario SPD would indeed run the ram at proper speeds---but the point is--its not always the case.

But your other suggestion of downloading and running CPU-Z is spot on. First determine if you have a need to go into manual settings just to get rated speed out of the ram. With luck, SPD will already have found the best standard settings.

As for the overclocker who pushes beyond rated speeds---they play a different game by the same rules.

 

[RonAKA]

Originally posted by: Lemon law
To RonAKA,
At least in my case there was a compelling reason to switch from SPD to manual. I had two sticks of mixed PC3200 dram, but somehow SPD decided to run them at less than PC2100 speeds. And playing with manual settings yielded a 50% memory throughput increase at zero overclocking in my case.

Understood.

 

[n7]

CPU-Z only shows the four main timings & command rate on the P5B-Ds.

If you wish to see what timings the 6 subtimings are running at, you need to either go into the bios, or run MemSet.

 

[Roguestar]

n7, was it a visible performance increase at all, or just a few milliseconds shaved off SuperPi? I assume those timings play second fiddle to the first four, and then again to the memory speed?

 

[n7]

Originally posted by: Roguestar
n7, was it a visible performance increase at all, or just a few milliseconds shaved off SuperPi? I assume those timings play second fiddle to the first four, and then again to the memory speed?

Oh, it's most definitely not noticeable for general use

It was noticeable in SuperPI though

 

[bloodandsoil]

Is there a program that will show me what those last 6 sub-timings are set to when I have "Auto" SPD selected in the BIOS?

 

[n7]

Originally posted by: n7
CPU-Z only shows the four main timings & command rate on the P5B-Ds.

If you wish to see what timings the 6 subtimings are running at, you need to either go into the bios, or run MemSet.

http://www.xtremesystems.org/forums/showthread.php?t=92190