Memory Timings Explained W/ Suggested Timings & Memset VS. BIOS

[Lsdmeasap]

First of all the basics

Rated Memory Timings

• CAS (tCL) Timing: CAS stands for Column Address Strobe or Column Address Select. It controls the amount of time in cycles between sending a reading command and the time to act on it. From the beginning of the CAS to the end of the CAS is the latency. The lower the time of these in cycles, the higher the memory performance.
  e.g.: 4-4-4-12 The bold “4” is the CAS timing.
• tRCD Timing: RAS to CAS Delay (Row Address Strobe/Select to Column Address Strobe/Select). Is the amount of time in cycles for issuing an active command and the read/write commands.
  e.g.: 4-4-4-12 The bold “4” is the tRCD timing.
• tRP Timing: Row Precharge Time. This is the minimum time between active commands and the read/writes of the next bank on the memory module.
  e.g.: 4-4-4-12 The bold “4” is the tRP timing.
• tRAS Timing: Min RAS Active Time. The amount of time between a row being activated by precharge and deactivated. A row cannot be deactivated until tRAS has completed. The lower this is, the faster the performance, but if it is set too low, it can cause data corruption by deactivating the row too soon.
  tRAS = tCL + tRCD + tRP (+/- 1) so that it gives everything enough time before closing the bank.
  
  e.g.: 4-4-4-12 The bold “12” is the tRAS timing.

(The 4-4-4-12 figure is just an example for main memory timings.)

These are the four timings that you would see when memory is being rated. It is in the order of CAS-tRCD-tRP-tRAS. The lower these timings, the higher the performance of the memory. Some motherboard manufacturers (DFI for example) list the timings in their bios CAS-tRCD-tRAS-tRP.


Certain memories can take tighter (lower) timings at higher speeds. These are the more expensive memory modules out of the bunch. There are also other timings to consider in your BIOS. Not all boards will have options like these.

Advanced Memory Timings

• tRRD Timing: (Act to Act Delay) Row to Row Delay or RAS to RAS Delay. The amount of cycles that it takes to activate the next bank of memory. It is the opposite of tRAS. The lower the timing, the better the performance, but it can cause instability.
• tWTR Timing: (Rank Write To Read Delay) Write to Read Delay. The amount of cycles required between a valid write command and the next read command. Lower is better performance, but can cause instability.
• tWR Timing: (Write To Precharge Delay)Write Recovery Time. The amount of cycles that are required after a valid write operation and precharge. This is to insure that data is written properly.
• tRFC Timing: (Refresh To Act Delay) Row Refresh Cycle Timing. This determines the amount of cycles to refresh a row on a memory bank. If this is set too short it can cause corruption of data and if it is too high, it will cause a loss in performance, but increased stability.
• tRTP Timing: (Read To Precharge Delay) Number of clocks that are inserted between a read command to a row pre-charge command to the same rank.
  
  Below Values are not in ALL BIOS's (See Below link for a FULL List of Values)
  
  
• tRTW/tRWT Timing: Read to Write Delay. When a write command is received, this is the amount of cycles for the command to be executed.
• tRC Timing: Row Cycle Time. The minimum time in cycles it takes a row to complete a full cycle. This can be determined by; tRC = tRAS + tRP. If this is set too short it can cause corruption of data and if it is to high, it will cause a loss in performance, but increase stability.
• tREF Timing: The amount of time it takes before a charge is refreshed so it does not lose its charge and corrupt. Measured in micro-seconds (µsec).
• tWCL Timing: Write CAS number. Write to whatever bank is open to be written too. Operates at a rate of 1T, but can be set to others. It does not seem to work with other settings than 1T on DDR. DDR2 is different though.
• Command Rate: Also called CPC (Command Per Clock). The amount of time in cycles when the chip select is executed and the commands can be issued. The lower (1T) the faster the performance, but 2T is used to maintain system stability. On Intel based machines, 1T is always used where the number of banks per channel are limited to 4.
• Static tREAD Value: (tRD) This setting is most commonly known as Performance Level or tRD this is the most effective chipset performance register available to adjustment. As FSB and memory speed are scaled/increased, tRD and Northbridge voltage will have to be increased to accommodate the additional data throughput. The idea when tweaking your system for the BEST performance is to run the tightest (Lowest) tRD possible at any given FSB or memory speed. See Below Link for more reading on this

Full List of Most All BIOS Memory Values

Some are covered here and some are not as they are not relevant to Most Gigabyte boards
Tweakers.fr

Conclusion

CAS-tRCD-tRP-tRAS are the main timings that are of concern to most users.

All of the other settings are only really changed when overclocking, or tweaking your timings. If you plan to stay at stock frequencies and timings, there is no real need to play with the other advanced memory settings.

Ram Multiplier Calculator
http://www.peakin.com/xbx2/calculato...fsb=320&mult=9


MemSet VS. BIOS Settings (Download Linked Below)





Suggested Settings for P35/P45 Boards

Performance Enhance________________ Standard

CAS Latency Time________________ 4/5
Dram RAS# to CAS# Delay_________ 4/5
Dram RAS# Precharge Delay________4/5
Precharge Delay (tRAS)___________ 12/15/18

The above ranges will be dependent upon your ram spec which should be listed on the package or sticker of your ram

The ranges below are meant to be used as stable stock timings that can be latter tested and lowered one by one with testing between each move.

The timings x2 in ()'s below are to be tested last only for benchmark purposes.

And just so everyone is clear on this the latter one being Static tRead Value May HARD FAIL for most all users and often cause a need to Clear CMOS if you attempt to use 5/6, but some will get it to work and it is worth the time and effort if you are into tweaking your ram to at least try it a few times. If you do decide to try it then please have the other subtimings loose when you first attempt it

Memtest86+ is suggested for memory testing (Download Linked Below)

ACT to ACT Delay (tRRD)________ 3-4
Rank Write to READ Delay (tWTR)_______ (4-6) 9-11 (Note Actual Value set in BIOS Vs. What system Uses will be 7+)
Write to Precharge Delay (tWR)________ 3-5 (Note Actual Value set in BIOS Vs. What system Uses will be 5+)
Refresh to ACT Delay (tRFC)___________ 38-42 (2X1GB) 52-62+ (2x2GB)
Read to Precharge Delay (tRTP)_________ 3-6 (Note Actual Value set in BIOS Vs. What system Uses will be 2+)
Static tRead Value (tRD)______________ (5/6) 7-10 (800Mhz) 7-12 (1066Mhz)
Static tRead Phase Adjust________ 1-31*

* Pertaining to Static tRead Phase Adjust: Leave on Auto or Zero Or 1-31 (This Adjustment is uncontrolled and subtracts from the Static tRead Value at random times and is suggested to not be used unless you really know what you are doing. For more in depth read about this setting you can have a look here >>>
AnandTech: The Gigabyte GA-X48T-DQ6 - Redefining the High End?

Also Some in depth Static tRead Value (tRD) discussion here as well
AnandTech: ASUS ROG Rampage Formula: Why we were wrong about the Intel X48

[Lsdmeasap]

MCH Voltages/tRFC (Refresh To Act Delay) & More Than 2 X 1GB of Memory

When using 2 X 2 or more of Memory you will have to add more MCH Voltage. How much is up to the ram you are using, the board itself, and overall memory performance.

Suggested MCH Voltage to add (Even for 2 X 1 GB) is +0.1V. When you start tweaking, Overclocking, or just plain using 2 X 2GB or more you will need to add More MCH Voltage. Amount will Vary but just moving up to +0.15V or +0.2V will usually do it for 2 X 2GB. More of course will need more.

Trial and error is the only way to know for sure how much your board and ram will need, but +0.3 is almost never necessary. If you find yourself thinking your board needs this much please ask someone as it is most likely you have some other setting that is "Off" that is affecting your stability and making you think you need more.

Refresh to Act Delay Or tRFC will have to also be adjusted when using more then 2 X 1GB of Memory. Normally a range between 52 and 62 will be fine for 2 X 2GB of ram, and with some fine tunning you can usually run at 48 or 50. More then 4GB will need more of course, but how much is again up to your Memory, Board and some patient testing.

Memset (LIVE Memory Tweaker and Value Checker)

MemSet is a tweaker which allow to change memory timings under Windows.
You can read principal and secondary timings, and eventually change these timings values. This is useful in checking values you set in the BIOS against what you get in windows, or to see what AUTO is giving you as a setting.

You can change ANY subtimings LIVE within windows and apply it, but do not save or set to run at startup. Make any changes you plan to keep in the BIOS and test them respectively. You cannot change Main timings with this program. And of course, YES you can crash or freeze your system changing values LIVE, if this happens to you do not worry simply shut down your PC and restart it all will be fine

Memset Live Memory Tweaker Homepage

Memset V. 4.0

-Use WinRing0 driver.
-Interface is the same for all chipsets/CPUs.
-Add support for Intel Core i7 CPU (Reading only).
-Loading time was improved.
-Improve frequency reading on Core i7.
-Improved reading SPD info on DDR2 & DDR3.
-Fixe frequency reading on some Core 2 Duo CPU.

Memset V. 4.0 Download


Memtest86+ (Memory Testing)

Memtest86+ - Advanced Memory Diagnostic Tool Download

When doing basic tests on new ram or just for general testing purposes you should let the test run on it's own for a few hours up to 24 if you have the time and don't mind.

When you are tweaking timings and just need some quick answers you can quickly see if your recent changes have made your ram unstable by choosing certain tests. Some say their own set of test #'s to use and they may differ from my own, so if you see someone else suggesting test #'s they that would be fine as well to, it is up to you.

What test #'s I use for basic speed testing to see if recent changes are causing errors quickly are #'s 2 & 5. I run test #2 for about 10 minutes and if I see no errors I will then run test #5 for a hour or so. If no errors are found then your changes are likely ok for the time being. Longer tests will let you know for sure though, but like I said here we are speed testing while doing a little bit of tweaking. If it is going to fail you think and are not so sure let #5 run for a while. It will fail on #5 if it is going to fail.

Below are Some BIOS examples, Sorry for the Resolutions I did not take them myself.

GA-P35 BIOS Example



GA-P45 BIOS Example




**SIDENOTE**

To run tests by number, you do this >>>
1. First press C

2. then 1

3. then 3

4. and finally select the test that you want to run

5. press Enter

6. and then 0 to get it running

I mention this because you may often see myself or someone else suggest only running certain tests by #'s at certain points. Which is what I do when fine tunning subtimings, I will run Test #2 and Test #5 for a variable amount of time between changing settings one a a time. After many moves though, please be sure to run some full tests for several hours


**NOTE**

On Some Gigabyte Mother boards you will need to use a hotkey to see all BIOS settings. These are either older boards or boards that have not updated BIOS's recently.

The Hotkey is Control + F1 (Ctrl + F1). You will need to push this Hotkey Combination on the MAIN or Front Page of the BIOS, the screen will then very quickly flash. After that you may go into the M.I.T section and ALL hidden settings will be shown. This will also enable hidden settings to be shown in ALL Sections of the BIOS not just the M.I.T. Section.


I would like to thank Merman our fellow board member for him suggesting this thread to me and I hope you all find it to be of at least a little help. If nothing else you will at least have more knowledge now then what you did before about Ram since you took the time to read this over

[Merman]

Wow! I didn't expect so much information. Excellent work.

I really like the settings numbered in MemSet. Now they should be referenced to recommendations. The first four settings are easy to see but after that it gets confusing.

Suggested Settings for P35/P45 Boards

(1) CAS Latency Time________________ 4/5
(2) Dram RAS# to CAS# Delay_________ 4/5
(4) Dram RAS# Precharge Delay________4/5
(5) Precharge Delay (tRAS)___________ 12/15/18

Maybe not so easy, did I get them right??? Hey I did get them right as I just read the NotePad. Duh. Lots of good info here and I may be reading too fast.

At first I didn't realize the second half recommendations are listed in the same order as the BIOS. Maybe a note that the second half recommendations are listed in BIOS order or re-arrange some of the notes below the BIOS settings???

I think people need to see at a glance and/or told that this is the BIOS setup Memory Options and reminded that for some boards Control F1 has to be entered at the main bios menu to see these options and value settings.

Maybe an image would help???



I also was going to suggest the Anandtech reference but you already did.

Thanks for the credit.

[Merman]

I was just reading this thread:

Re: GA-EP35-DS3L vcore problem after Standby

--------------------------------------------------------------------------------

Well yes, and no. 2.1 is likely for sure all your ram needs, but with the proper timings as well. If you dont want to mess with tweaking it for a while then I would suggest you use 2.2 and please do you ram a favor and put a fan over it.

You will need a RMA soon for sure with 2.2, that is the MAX warrantied voltage, not what is needed to run stable.

I would suggest this for 4x1GB >>>
Performance Enhance = [Standard]

CAS Latency Time________________ 4
Dram RAS# to CAS# Delay_________ 4
Dram RAS# Precharge Delay_______4
Precharge Delay (tRAS)__________ 12

Start with the higher settings, moving later ONE AT A TIME lower and test after each move

ACT to ACT Delay (tRRD)_________ 3-4
Rank Write to READ Delay________ 9-11
Write to Precharge Delay_________ 3-5
Refresh to ACT Delay______________ 42-52
Read to Precharge Delay__________ 3-6
Static tRead Value_______________ 7-10
Static tRead Phase Adjust________ Auto << Leave ALWAYS

System Voltage Control____ [Manual]
DDR2 OverVoltage Control__ [+0.3V]
PCI-E OverVoltage Control_ [Normal]
FSB OverVoltage Control___ [+0.1V]
(G)MCH OverVoltage Control [+0.1V - 0.15V]

Do you think :

1. Performance Enhance setting should be listed in this guide too???

2. Does Refresh to ACT Delay settings depend upon memory capacity??? 2,4 or 8gigs.

3. Should System Voltage Controls concerning memory also be included in this guide???

[Merman]

I see the P45 Advanced Timing Control is different. The timing options order is the same without some of the nomenclature but Channel A and B have more adjustments. ???

[Lsdmeasap]

Damn ya! Na, Just kidding

Thanks for the great input, I thought I may not need to go that deep yet!

I will work on your suggestions over the weekend.

As for your Refresh to Act question, YES it is absolutely dependent on how many GB you have installed and really what you will end up with may be less then I stated after tweaking. And that direct thread I believe I just gave that user those numbers to try as he in my opinion was having issues with incompatible ram so I was seeing if I could help him get anywhere with it. (*See my not below concerning this)

52-62 is a good starting point for 2x2GB, some will get down to 48-50 with proper testing. 4X1GB is about the same but may end up a little higher after tweaking and testing all depending on the Ram's bandwidth and quality

* I was going to also add in my suggestions for and against ram brands but I thought it may be too much for now. And most people, even if they do ask, do not want to hear that there 4-8GB of brand new ram is not on the QVL or in my opinion is incompatible and end up trying to blame the board or something else when they should be doing a RMA soon as possible

I appreciate your suggestion and I will work on getting them added in this weekend for sure.

I do not have X38/X48 Or P45 which have some of the more advanced options to post my own images, if you get time could you possibly send me full size images of the MIT section of a P45 BIOS? If so be sure you include the advanced memory page where you would hit enter to see. If not I am sure I can find some online.

Thanks again for all your suggestions, and Ohh yeah I will also add in voltages this weekend as well

[Merman]

I do not have X38/X48 Or P45 which have some of the more advanced options to post my own images, if you get time could you possibly send me full size images of the MIT section of a P45 BIOS? If so be sure you include the advanced memory page where you would hit enter to see. If not I am sure I can find some online.

I have a GA-P35-DS3L but will look on line for these images to save you some time. What I find I will send by PM.

Thanks for your efforts.

[mattlyall06]

yeah, wow, answered my questions before i had to ask.

id be interested to hear your recommendations for ram brands.. ill be looking to build myself another computer, and i'd like to stick with a gigabyte mobo because thats what im using now, and it was easy for me to overclock. also 8gb of ram (vista x64 kicks ass ).

thanks for all your efforts lsd

[Lsdmeasap]

Anytime, I plan to try to find time to update this a bit more tonight or soon as I can.

[Johnny123]

Kingston ram i've found works well (i've built a few computers with gigabyte boards and kingston ram with no probs).