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Manual entry of memory timings

Last response: in Memory
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March 22, 2007 1:25:58 AM

Got a question on this memory here http://www.crucial.com/store/partspecs.aspx?imodule=BL1...

The specs say that the timings are 4-4-4-12 which I believe corresponds to CAS-tRCD-tRP-tRAS. How do I manually change those values in the BIOS?

In my BIOS (Asus P5B-Deluxe motherboard), 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

And I downloaded CPU-Z and here are the results:

Under the Memory Tab:

Type: DDR2
Size: 2048 MBytes
Channels# Dual
Frequency: 400.0 MHz
FSB:D RAM: 2:3
CAS# Latency: 5.0 clocks
RAS# to CAS# Delay 5 clocks
RAS# Precharge: 5 clocks
Cycle Time (Tras): 18 clocks
Command Rate: 2T

Under the SPD tab (Slot #1 and Slot#2 are identical except for Serial Number):

Module Size: 1024 MBytes
Max Bandwidth: PC2-6400 (400 MHz)
Manufacturer: Crucial Technology
Correction: None
EPP: yes
Frequency: 400 MHz --- 500 MHz
CAS# Latency: 4.0 --- 5.0
RAS# to CAS#: 4 --- 5
RAS# Precharge: 4 --- 5
Tras: 12 --- 15
Trc: 24 --- 30
Command Rate: 2T --- 2T
March 22, 2007 11:56:52 PM

Looking at the memory you have, it says that it is SLI-ready. That means that memory companies, such as Crucial, can put two or more spd settings onto the modules to make overclocking easier.

Now, your board also has to be SLI-ready or EPP-ready(the same thing if relating to memory). If your board is, then there will be an option in your bios to enable EPP (or SLI) for your memory. Then the bios would pick up on the enhanced performance profile (EPP) setting on your modules, and it would then clock them at the 4-4-4-12 timings.

But if you do not have an EPP ready board (which it doesn't look like it is), you can just change the timings manually just by pushing enter on the cas latency (4), ras to cas delay (4), ras precharge (4), and ras activate to precharge (12). Leave the other ones at auto, then change the voltage for the modules to what they are rated at (probably 2.1 or 2.2V). Save and exit the bios, start up cpu-z again, and see what it says.
March 23, 2007 12:37:44 AM

what he said - but your board is not SLi ready. I have the same RAM and set it to 4-4-4-12 tonight. set the CAS to 4, tRCD to 4, tRP to 4 and tRAS to 12, then the tRC to 24. Command should be 2T. Make sure you up the memory voltage too. It will be 1.8v standard, you want 2.2v

I did exactly this a couple hours ago. running nicely :) it will actually run at 1066MHz at CAS 5 if you wanted. not sure how to do that yet though.. still learning
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March 23, 2007 2:45:07 AM

Quote:
...then the tRC to 24.


What is tRC?
March 23, 2007 4:16:52 AM

Quote:
it will actually run at 1066MHz at CAS 5 if you wanted.


What does that mean? I'm sort of lost on this.
March 23, 2007 3:15:46 PM

As you can tell, 1066 MHz is better than 800 MHz, as it is a faster frequency. But at 1066, you need a slower timing, hence the Cas latency has to be at 5 to make the memory stable. There are a lot of different arguements at which is better, 1066 5-5-5-12 or 800 4-4-4-12, so you can decide by benchmarking when you get both up and running.

Now, what processor do you have? With AMD, usually if you change the FSB to 266, the cpu multiplier to 10, up the cpu voltage a little (maybe 1.45 - 1.5V), and up the memory voltage to 2.2-2.3V, you can usually achieve 1066 with 5-5-5-12 stability. (It also matters if this memory can actually hit 1066....)
March 23, 2007 4:25:53 PM

Quote:
There are a lot of different arguements at which is better, 1066 5-5-5-12 or 800 4-4-4-12, so you can decide by benchmarking when you get both up and running.


In general tighter timings are more important than bandwidth in game performance. If this machine is going to be purely for benchmarking then higher bandwidth will improve scores.
March 23, 2007 5:45:07 PM

Quote:
Got a question on this memory here http://www.crucial.com/store/partspecs.aspx?imodule=BL1...

The specs say that the timings are 4-4-4-12 which I believe corresponds to CAS-tRCD-tRP-tRAS. How do I manually change those values in the BIOS?

In my BIOS (Asus P5B-Deluxe motherboard), 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

And I downloaded CPU-Z and here are the results:

Under the Memory Tab:

Type: DDR2
Size: 2048 MBytes
Channels# Dual
Frequency: 400.0 MHz
FSB:D RAM: 2:3
CAS# Latency: 5.0 clocks
RAS# to CAS# Delay 5 clocks
RAS# Precharge: 5 clocks
Cycle Time (Tras): 18 clocks
Command Rate: 2T

Under the SPD tab (Slot #1 and Slot#2 are identical except for Serial Number):

Module Size: 1024 MBytes
Max Bandwidth: PC2-6400 (400 MHz)
Manufacturer: Crucial Technology
Correction: None
EPP: yes
Frequency: 400 MHz --- 500 MHz
CAS# Latency: 4.0 --- 5.0
RAS# to CAS#: 4 --- 5
RAS# Precharge: 4 --- 5
Tras: 12 --- 15
Trc: 24 --- 30
Command Rate: 2T --- 2T

I have the exact same setup and problem. Any change I make seems to make the system unstable. My RAM is DDR2 800 rated at CL4. my FSB is 400 Mhz. So I think I should not have any trouble actually getting CL4 !!
Is there any general procedure I can do slowly lower the timings?
Thanks!
March 23, 2007 11:27:11 PM

Remember that the rating timings probably require a higher-than-standard voltage for the memory. Once you've gotten the appropriate memory voltage number from the memory manufacturer, go into the BIOS and set the memory voltage to that value. Save settings and restart. After that, you should be able to set the appropriate timings in the BIOS.
March 24, 2007 3:19:00 AM

Quote:
Remember that the rating timings probably require a higher-than-standard voltage for the memory. Once you've gotten the appropriate memory voltage number from the memory manufacturer, go into the BIOS and set the memory voltage to that value. Save settings and restart. After that, you should be able to set the appropriate timings in the BIOS.

Thanks, I'll try that.
What is the HIGHEST voltage you think Corsair 6400 CL4 can go?
At least high enough to fail boot rather than fry the RAM.
(I may not have the good Micron RAM)
March 24, 2007 3:46:47 AM

My Crucial Ballistix is 2.2V but my motherboard (Asus P5B-Deluxe) does not have a setting for 2.2. It has a setting only for 2.15 and 2.25. So which one should I select?
March 24, 2007 4:48:52 AM

I think Corsair guarantees its memory up to 2.1V.

For bas: try 2.15V first and see if it checks out OK with memtest86+; if not, bump it to 2.25V and test again.
March 24, 2007 5:36:52 AM

Quote:
I think Corsair guarantees its memory up to 2.1V.

For bas: try 2.15V first and see if it checks out OK with memtest86+; if not, bump it to 2.25V and test again.

OK thanks. Will do.
!