Setting RAM timings 3

[Nelviticus]

Hi there, I'm just wondering how to configure my motherboard to run my RAM at optimal settings. I have heard that if you leave it in 'auto' mode it uses very conservative timings.

I have four 1GB sticks of Corsair XMS2-6400 CL5, which apparently "has been verified to operate at 800MHz at the low latencies of 5-5-5-12-T1".

My motherboard is an Asus P5B. In the 'Northbridge' settings there is an option to 'Configure DRAM timing by SPD', which is normally set to 'enabled'. If I set it to 'disabled' I get access to a load of extra settings as follows (numbers show what they're set to by default, with the allowable ranges in brackets):

DRAM CAS# latency: 5 (3-6)
DRAM RAS# to CAS# delay: 6 DRAM clocks (2-6)
DRAM RAS# precharge: 6 DRAM clocks (2-6)
DRAM RAS# activate to precharge: 15 DRAM clocks (4-18)
DRAM write recovery time: 6 DRAM clocks (2-6)
DRAM TRFC: 42 DRAM clocks (20, 25, 30, 35 or 42)
DRAM TRRD: 10 (0-15)
Rank write to read delay: 10 (0-31)
Read to precharge delay: 10 (0-15)
Write to precharge delay: 10 (0-31)

I also have a setting called 'Static read control' which can be Auto, Disable, Fast or Faster.

Any idea what I should set all these values to so that my RAM runs at optimal speed? I am not interested in over-clocking it.

Thanks

Nelviticus

 

[paparazi]

Look at the spec sheet for your memory either on the information that came with the ram or the website.
Adjust only those settings corresponding to the 5-5-5-12
and the increased voltage that is required to run at these timings otherwise it won't boot or if it boots it will be unstable.
If you can see a T1/T2 setting then obviously set to T1 but not all bios has the adjustment.

Martin



On wings like angels whispers sweet
my heart it feels a broken beat
Touched soul and hurt lay wounded deep
Brown eyes are lost afar and sleep

 

[Freestone]

I am fairly certain this document explains the timings you have listed. It is a bit dated, especially shown with the CAS Latencies of 2 and 2.5, so you may want to confirm elsewhere.

http://www.corsair.com/_appnotes/AN501_Latency_Settings_and_Performance.pdf

If the document holds up, then the 5-5-5-12-T1 would correspond directly with the first four timings you listed:

DRAM CAS# latency: 5 (3-6) 5
DRAM RAS# to CAS# delay: 6 DRAM clocks (2-6) 5
DRAM RAS# precharge: 6 DRAM clocks (2-6) 5
DRAM RAS# activate to precharge: 15 DRAM clocks (4-18) 12

I don't see the setting for the command rate (T1). Martin addressed this in his post.

I never heard of a Static read control. But a search found me this article from the ever informative AnandTech site. I haven't digested the article enough to even pretend to be able to give advice about this setting, and since you are not into overclocking, Auto would probably be the safest bet.

http://www.anandtech.com/cpuchipsets/intel/showdoc.aspx?i=3184&p=8

 

[Nelviticus]

Thanks both, that Corsair article is actually very interesting although it's quite old. They benchmark changes in individual settings to find out how much impact each one has.

I have set my first four values to 5, 5, 5 and 12 and the system is stable although not noticeably faster. I just ran a game benchmark (X3 Reunion) and it's actually very fractionally slower than the last time I ran it! The graphics card is the bottleneck in that game though so I wouldn't expect to see much, if any, improvement.

I wasn't expecting a noticeable speed-up really but just wanted to make sure I had optimum settings. I'm happy now, so thanks!

Regards

Nelviticus

 

[BadBigBen]

Hola, Nelveticus, actually what you are doing is setting the timing manually what the AUTO or BY SPD does (there are some instances that the SPD is read incorrectly but that should have been ages ago)...

more at:

http://www.simmtester.com/page/news/showpubnews.asp?num=101

and

http://www.overclock.net/intel-memory/9981-ram-timing-explained.html

Ben

"If it works don't fix it! If it doesn't use a sledgehammer..."

 

[Nelviticus]

Aha. Well in that case I've just re-set it back to 'auto'! Maybe one day I'll feel brave enough to experiment with over-clocking.

Regards

Nelviticus

 

[paparazi]

Agreed! the timings are sometimes (not always)automatically detected and set by the bios.The trouble is I've yet to see a motherboard automatically increase ram voltage to the required defaults needed to run at these tighter timings.
It is very common to see the ram manufacturer stating a 0.1-0.3 volt increase at default timings to run this faster ram stabley. If you do one without the other don't be too suprised when you get blue screens and restarts.
Martin


On wings like angels whispers sweet
my heart it feels a broken beat
Touched soul and hurt lay wounded deep
Brown eyes are lost afar and sleep