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

[Merman]

I have been tweaking my memory and thought I would mention some of my experiences.

My system:
GA-P35-DS3L
E8400 at 3GHz and 3.6GHz
Corsair Memory CM2X1024-6400C4 version 6.2
PSC 128Mx8 memory chips
DDR2 at 400MHz
2-1gig sticks rated at 444-12 at 2.1v
I have been able to run it at 1.8v even at 960MHz
SPD: 555-18, tRC 22, 1.8v at 400MHz per CPU-Z
Everest adds:
tRRD 3
tWTR 3
tWR 6
tRFC 42
tRTP 3

This ram really likes the SPD specs. Not surprising I suppose. :)

I found that most of the settings stay the same from 3GHz to 3.6GHz. Except for the main settings of 444-12 to 555-18 and tWTR and tWR have a mind of their own.

WTR and WR will crash Vista 32 when trying recommended settings and MemSet will show different settings than set in the BIOS. ???

I suppose more important tRD and tRFC seem to be the most important settings or show the most improvement other than CPU speed.

All these settings are at Memory multiplier of 2.4. At 3.6GHz I tried changing to 2.0 and Vista crashed hard. That supprised me. The memory was running stable at 960MHz but reducing it to 800MHz would crash the system???

Settings:

.......................3GHz..........3.6GHz....... ...Recommended.....MemSet diff

Perf. Enhanced Turbo........Standard

Memory Multiplier Auto.........Auto
Frequency..........800...........960

Standard Timing 444-12.......555-18

Advanced Timing:
tRRD...................3................3......... ............3-4
tWTR..................3................3.......... ...........9-11.............10..&11
tWR....................6................6......... ............3-5...............13..&14
tRFC..................42...............42......... ...........38-42
tRTP...................3.................3........ .............3-6...............5..&5
tRD.....................6.................6....... ..............7-10
Phase Adj.... left on Auto.

Any comment or suggestions???

[Lsdmeasap]

First off, sorry man I have been so busy I have yet to have time add in things we have discussed. But I have been writing them up and collecting other info and doing some in depth reading about skew control as well. I will get it done trust me.

Sorry I forgot to add a similar note to tWR that I added to tWTR, they both will always be different then set in the BIOS, I will add the other note in. I think it is by 8-9+ depending for tWR. The thing I guess I need to also address is between chipsets sometimes tWTR needs to be set to whatever in the BIOS that equals 11-12 in Memset, which is often 4-5. tWR is a bit different on how things should be set depending on a few other factors and what things are set on.

When you say crash vista when trying "Recommended" settings, who's recommended settings are you referring to?

Yes, tRD is the single most thing that affects Memory Bandwidth that is why it is often called the Performance Level.

As for your crashing, what settings in the BIOS did you have that make 800 crash on you? If it was tRD of 6 then that is likely the setting that caused it, it may have worked for you at 2.4 multi because of a strap being used or not.

I guess I would need a better table of what you used at each to understand, you saying things about the SPD have me unclear what you used even with your table. Since the SPD is not used in Intel boards fully, nor does the SPD contain all settings info I am not sure if you chose SPD from memset or what you were seeing in AUTO on the left in the BIOS (Which would be incorrect, often change, and ONLY be used at that specific time in the BIOS)

Yes AUTO does try to read SPD info in a Intel Board and sometimes gets part of it correct. Intel has been working on getting this better like Nvidia Chipsets EPP and how they read them. They have implemented XMP, which is similar.

SPD is programmed in memory to go above JEDEC standards and is made to be read by EPP programming, which is why AUTO often in not correct it getting these settings

[Merman]

Originally Posted by Lsdmeasap

First off, sorry man I have been so busy I have yet to have time add in things we have discussed. But I have been writing them up and collecting other info and doing some in depth reading about skew control as well. I will get it done trust me.

No need to apologize. You answer all the questions on this board and helping everyone should be more than enough. I thought this guide would help ease your load and give everyone a solid easy to find reference. With that in mind I see no reason to rush.

Originally Posted by Lsdmeasap

Sorry I forgot to add a similar note to tWR that I added to tWTR, they both will always be different then set in the BIOS, I will add the other note in. I think it is by 8-9+ depending for tWR. The thing I guess I need to also address is between chipsets sometimes tWTR needs to be set to whatever in the BIOS that equals 11-12 in Memset, which is often 4-5. tWR is a bit different on how things should be set depending on a few other factors and what things are set on.

Interesting. I see I'm just getting my feet wet.

Originally Posted by Lsdmeasap

When you say crash vista when trying "Recommended" settings, who's recommended settings are you referring to?

The recommended settings in this guide. Its basically tWR as when my settings are lower than recommended I don't try going lower. My tWR setting is 6 and going lower hard crashed Vista. By hard crash I mean Vista stopped giving a warning that it stopped so no damage is done.

Originally Posted by Lsdmeasap

Yes, tRD is the single most thing that affects Memory Bandwidth that is why it is often called the Performance Level.

As for your crashing, what settings in the BIOS did you have that make 800 crash on you? If it was tRD of 6 then that is likely the setting that caused it, it may have worked for you at 2.4 multi because of a strap being used or not.

That doesn't make sense to me. The ram was running stable at 960MHz, CPU at 3.6GHz with tRD at 6 with the multiplier on Auto. I was thinking of upping the CPU frequency but wanted to set memory frequency to 800MHz first. I changed the mulitplier from Auto to 2.0. The system rebooted twice and reset the BIOS to stock settings. Doesn't make sense to me maybe I made some other mistake. ???

Re-reading your reply mentioning the "strap" my BIOS has on the right markings to show which multiplier coincides with which strap. At least that is my uderstanding. ??? Seems I have to take another look at this and fully understand this section of the F8 final bios for the P35-DS3L.

Though for 400MHz memory to run at 960MHz with a 400MHz FSB, its 400*2.4=960MHz. So 400*2=800MHz and stock 333*2.4=800MHz Am I missing something here???

Originally Posted by Lsdmeasap

I guess I would need a better table of what you used at each to understand, you saying things about the SPD have me unclear what you used even with your table. Since the SPD is not used in Intel boards fully, nor does the SPD contain all settings info I am not sure if you chose SPD from memset or what you were seeing in AUTO on the left in the BIOS (Which would be incorrect, often change, and ONLY be used at that specific time in the BIOS)

Sorry I thought my post was clear. The SPD settings were taken from CPU-Z and Everest. See the first paragrph of my last post listing my system. My understanding is these programs are reading the SPD info stored in the memory. In CPU-Z the info is under SPD. In Everest the info is under Motherboard/SPD/Memory timings.

My table of Settings shows BIOS settings for 3 and 3.6GHz, the guide's recommended settings, and the MemSet column showing any different settings than what was set in BIOS. As you explained tWTR and tWR should report a different setting than what was set in BIOS. Though tRTP also shows a small different setting.

Originally Posted by Lsdmeasap

Yes AUTO does try to read SPD info in a Intel Board and sometimes gets part of it correct. Intel has been working on getting this better like Nvidia Chipsets EPP and how they read them. They have implemented XMP, which is similar.

SPD is programmed in memory to go above JEDEC standards and is made to be read by EPP programming, which is why AUTO often in not correct it getting these settings

The only Auto setting used was the Memory Multiplier. I know that 2.4 was used because it shows the memory frequency in the BIOS and CPU-Z confirmed it though it reports the setting as 5:6. Though the P-35-DS3L did read the memory's SPD very accurately.

[Lsdmeasap]

The recommended settings in this guide. Its basically tWR as when my settings are lower than recommended I don't try going lower. My tWR setting is 6 and going lower hard crashed Vista. By hard crash I mean Vista stopped giving a warning that it stopped so no damage is done.

This is likely only because you are using tRD of 6, which as you see I suggested against for a few reasons. Mostly though because the guide was Meant for "General Getting your board up and running smoothly" and not a full "Tweaking" Guide. Which would be using 6 possibly on some boards depending on the quality and bandwidth of the ram at hand, along with a different set of most other settings being optimal

Re-reading your reply mentioning the "strap" my BIOS has on the right markings to show which multiplier coincides with which strap. At least that is my uderstanding. ??? Seems I have to take another look at this and fully understand this section of the F8 final bios for the P35-DS3L.

Though for 400MHz memory to run at 960MHz with a 400MHz FSB, its 400*2.4=960MHz. So 400*2=800MHz and stock 333*2.4=800MHz Am I missing something here???

Well there is a internal 333 and 400 Strap for the NB weather it is shown as a Option or not in your Memory Multi choices. And again tRD of 6 with either strap may or may not work at any freq, depending on the other settings

Sorry I thought my post was clear. The SPD settings were taken from CPU-Z and Everest. See the first paragrph of my last post listing my system. My understanding is these programs are reading the SPD info stored in the memory. In CPU-Z the info is under SPD. In Everest the info is under Motherboard/SPD/Memory timings.

My table of Settings shows BIOS settings for 3 and 3.6GHz, the guide's recommended settings, and the MemSet column showing any different settings than what was set in BIOS. As you explained tWTR and tWR should report a different setting than what was set in BIOS. Though tRTP also shows a small different setting.

Ahh, Ok I see what you mean now, I thought maybe you was saying the "AUTO" or left in the BIOS was what you thought SPD setup was, You can also use the SPD button in Memset (Just incase you didnt see it)

tRTP should be as set in the BIOS, does it always vary for you? If so, that could possibly be part of the factors that make the ram not fully compatible in my book with GA boards. I have often wondered what all those factors are but will likely never know

The only Auto setting used was the Memory Multiplier. I know that 2.4 was used because it shows the memory frequency in the BIOS and CPU-Z confirmed it though it reports the setting as 5:6. Though the P-35-DS3L did read the memory's SPD very accurately.

Sorry, what I meant to better say was intel P35 Chipsets do not accurately "Use" the SPD info for AUTO settings properly.

And also keep in mind any SPD setting you see is for use at 800MHz speeds. You will have better luck and performance with a tRD of 7 with tighter other timings Vs. tRD of 6 with others being loose

But in the end, it all adds up to the memory's compatibility with the board, Chipset Performance and heat, and the actual Ram quality or bandwidth it provides.

And of course what voltages are being used in the NB and Ram, and at what strap/FSb is being used. I could provide you with a Very indepth reading on Straps if you would like

[Merman]

Originally Posted by Lsdmeasap

tRTP should be as set in the BIOS, does it always vary for you? If so, that could possibly be part of the factors that make the ram not fully compatible in my book with GA boards. I have often wondered what all those factors are but will likely never know

tRTP was always different than the BIOS settings even with tRD set at 7.

Originally Posted by Lsdmeasap

And also keep in mind any SPD setting you see is for use at 800MHz speeds. You will have better luck and performance with a tRD of 7 with tighter other timings Vs. tRD of 6 with others being loose

All memory settings were set to Auto to overclock the CPU to 3.6GHz. Then I started tweaking the memory settings. tRD was set at 7 by the Auto BIOS settings and the last setting changed because I didn't think it would run at 6. Other than the overclock this setting did the most to improve memory benchmarks to the tune of 500MB in Everest Memory Read. It also set the lowest latency of 59.4. Since 6 worked to my surprise I tried 5 but the system locked up. No major crash like some of the other settings.

Originally Posted by Lsdmeasap

But in the end, it all adds up to the memory's compatibility with the board, Chipset Performance and heat, and the actual Ram quality or bandwidth it provides.

And of course what voltages are being used in the NB and Ram, and at what strap/FSb is being used. I could provide you with a Very indepth reading on Straps if you would like

I understand. I suppose I could tweak this memory even more as it is running at stock voltage of 1.872v as is the FSB and MCH. But since it is running so well as is I may not try for more. I am also tired of all the rebooting and some hard crashes while reaching the limits.

Is this the article you were thinking about linking??? If not please do give the link.

AnandTech: ASUS ROG Rampage Formula: Why we were wrong about the Intel X48

This one about tRD and memory tuning is also good and I will be re-reading both. I find as I get more experience I understand the concepts better and the articles are so technical I absorb more when reading them again. I suppose that is just studying and learning in general for all us non geniuses.

AnandTech: Overclocking Intel's New 45nm QX9650: The Rules Have Changed

[Merman]

After writing about not thinking tRD6 would work at 3.6GHz I started thinking that I didn't think of going lower at 3GHz.

Well I just tried tRD5 at 3GHz and it works fine. Memory Read just went up 300MB and latency went down about 4ns.

Well I'm off to finish the news and get ready for Hurricane Fay.

[Lsdmeasap]

WOW trd 5 eh, Post some screenies of Comparision bandwidth between 5-6 and 7 if you dont mind, Id like to see

[kpo6969]

Here's my P35-DS3L
E8400 @ 3.6
2x2GB PC8000 @ 1000mhz
4:5 divider 5-5-5-12
Performance Level 6

http://i239.photobucket.com/albums/f...69/Memset2.jpg

[Merman]

http://i295.photobucket.com/albums/m...ceLevel7-1.jpg

[Merman]