How to set up GTL Ref Values for 45nm & 65nm

[seban]

Hey !

Yup happy new year to all of ya ppl

I got little present for every one for new year .

It is simple Excel file which is counting GTLs and NB GTL as well as new Multiplier for you and few other minor values for given Vtt. It is nothing special but saves time and allows to tweak GTLs without asking for help and getting too much into it.

How to use it:

First type in desired / currently used vtt voltage as in your bios (or rather the way it looks loaded in Everest for example - but bios one is also working fine)

Secondly put some correction numbers and watch how GTL values are changing (Max and Min values of GTL for given VTT are also shown there).

The goal is to figure out which GTL works best for you for one VTT - in most cases the same GTLs voltages will work for different VTTs or very similar ones (or sometimes not ). So when we switch Vtt we would need to adjust GTLrefs to values which will give same or close to same GTLs as working previous ones for different vtt.

Anyway have fun using it, I created it to make my life easier and it does the job.

PS. There are 2 sets of values to compare between different VTT.
PS2. This calculator is made for MF2 board but will work with all boards that got correction number in equation (like +40 or - 20 and so on).

[CryptiK]

You too mate! Kickin back at home isn't all that bad, it's something different than the usual!

Ahh nice mate, same here, just having a quiet one in for once too Thanks too for the descriptions of the GTL's you provided, I couldn't have said it any better myself.

Hey !

Yup happy new year to all of ya ppl

***snip***

You too mate, hope you're having a good one.

Also thanks for taking the time to make up that spreadsheet, I have added it and your description to the first post.

[Ghostleader]

Do different chipset have different CPU, NB GTL as default.

Do P45 and X48 have the same

Example:

GTL Ref 0 = ,635
GTL Ref 1 = ,667
GTL Ref 2 = ,635
GTL Ref 3 = ,667

Is´t the CPU who determent what CPU GTL ref there´s, 45nm, 65nm or is´t the chipset.

What determent the NB GTL ref, does X48 and P45 chipset have the same GTL ref and does´t change if I run 45nm or 65nm CPU.



I run a EP45-UD3P board with a E8400@FSB 500 and I found that the most stable CPU ref are ~,635 and NB ref ~,600, the higher FSB the lower NB ref.

With my Q6600@FSB 475 I found that the most stable CPU ref are ~,667 and NB ref ~,700 the higher FSB the higher NB ref.


I have read the whole thread but I still think all this is quite confusing.

I understand that there´s a lot of trail and error also involved in this, I try different settings and I´m learn new this all the time.

Is there anyone how can answer me questions it will be much apprecieted.

[CryptiK]

Do different chipset have different CPU, NB GTL as default.

Do P45 and X48 have the same

Example:

GTL Ref 0 = ,635
GTL Ref 1 = ,667
GTL Ref 2 = ,635
GTL Ref 3 = ,667

**No not every board either X48 or P45 has the same setup, it depends on how the company wants to configure the BIOS options.

Is´t the CPU who determent what CPU GTL ref there´s, 45nm, 65nm or is´t the chipset.

**It's a combination of both the CPU and the individual board, for example if you keep the same CPU and replace the board with the exact same board again, you may need to re-adjust the GTL Refs as each set of board components/circuits behave slightly differently and give different resultant voltages even though you have set the BIOS options the same.

What determent the NB GTL ref, does X48 and P45 chipset have the same GTL ref and does´t change if I run 45nm or 65nm CPU.

**No the default GTL Ref multi of the X48 is different to the P45. What you set it to changes depending on the individual board (what is good for one board may nt be good for another board of the same type) and also if you run a 45nm or 65nm CPU, if you run a quad or a dual core, if you run 2GB or 4GB of ram, and if you run Crossfire or just a single card. It must be tuned for your individual components.


I run a EP45-UD3P board with a E8400@FSB 500 and I found that the most stable CPU ref are ~,635 and NB ref ~,600, the higher FSB the lower NB ref.

With my Q6600@FSB 475 I found that the most stable CPU ref are ~,667 and NB ref ~,700 the higher FSB the higher NB ref.


I have read the whole thread but I still think all this is quite confusing.

I understand that there´s a lot of trail and error also involved in this, I try different settings and I´m learn new this all the time.

Is there anyone how can answer me questions it will be much apprecieted.

I have answered in your quote as best I can. HTH.

[mikeyakame]

Heres a stab in the dark as to why there appears to be a small difference between X48 and P45 chipsets for GTL, it's just a shared thought.

P45 chipsets have a feature called CPU Margin Enhancement at least on Asus bios', what Intels official name is I don't know. From the little I know and I can figure out, the Margin Enhancement is a feature to address the electrical and physical constraints the front side bus had reached for the X48 based chipsets. These are most likely preset values either by OE or Intel that set up the signal skewing for the FSB/CPU clock waves to minimize clock jitter and ringback on the receiver, slew rate compensation, etc. Why you ask? AGTL+ is designed with limit of 400MHz on BCLK and beyond that integrity of the system can't be guaranteed. So P45 being mainstream and last ditch effort on FSB chipset to go beyond theoretical limits, this was added.

Now the point of the previous paragraph is, these presets most probably compensate for a percentage of signal problems that occur with high FSB frequencies that on the X48 chipset we we're using varying GTL Reference Points to handle compensation for clock signal integrity loss.

This is just a shot in the dark at why. None of us will ever know for sure, just theories and speculation.

You'll probably find that Asus' option names, Compatible / Optimal / Performance actually are presets for FSB frequency ranges. Compatible might be < 400MHz, Optimal 400-500MHz, Performance 500MHz ->. Thats just an example as its not that simple, but there will be ranges of frequencies that can be probably be compensated for with a margin of accuracy before those preset values go out of range.

If there is one thing that sucks though, it's that Asus, DFI, etc don't document what these settings and values do because they want to keep their design edge on their competitors products. This unfortunately has the consequence of us the guy who buys the product and uses it having to figure out what "insert corny performance name" option actually does and how it effects every other setting. I love having such flexibility, but some day the price of it without documentation that at least outlines its use it'll be too much for anyone.

[Ghostleader]

Thank you CryptiK and mikeyakame

But how do I know what the default value for CPU GTL ref are when I calculate, lets say Q6600 on a P45 board and I can set the GTL for all cores.

Are the default (auto) like this on a P45 board

GTL Ref 0 = ,635
GTL Ref 1 = ,667
GTL Ref 2 = ,635
GTL Ref 3 = ,667

And if I want ,667 on all cores I hade to ad (+) some (how much is depended on the VTT value) for 0 and 2 and let the 1 and 3 left at auto so they all are at ,667.

[mikeyakame]

Problem I've found on P45s is you dont know what the default should be, because of internal adjustments made by the bios code on top of changes you make! You just need to figure it out through a little trial and error is all.

[CryptiK]

Thank you CryptiK and mikeyakame

But how do I know what the default value for CPU GTL ref are when I calculate, lets say Q6600 on a P45 board and I can set the GTL for all cores.

Are the default (auto) like this on a P45 board

GTL Ref 0 = ,635
GTL Ref 1 = ,667
GTL Ref 2 = ,635
GTL Ref 3 = ,667

And if I want ,667 on all cores I hade to ad (+) some (how much is depended on the VTT value) for 0 and 2 and let the 1 and 3 left at auto so they all are at ,667.

I can say for sure the Maximus II Formula has the GTL Ref options as:

GTL Ref 0 = ,635
GTL Ref 1 = ,667
GTL Ref 2 = ,635
GTL Ref 3 = ,667

But with other boards it may be different, also some boards tie two GTL Refs together (ie: 0/2 & 1/3) so you only have two adjustments possible, not four. In this situation 0/2 usually = 0.635x and 1/3 usually = 0.667x but unless they state what it is in the BIOS or in the manual it's anyone's guess.

EDIT - as Mikey said though there is often adjustments going on behind what you are doing and as such are beyond your control, so don't focus on what they are originally but through trial and error establish what settings give you the best performance and stability.

[Ghostleader]

Thank you again CryptiK and mikeyakame

I get the picture.


Run Prime95 small with a little lower vcore the stable and see which core that fails and then adjust that GTL for that core and run Prime again.

Is this a good way to tune GTL?

or how do you guys test which GTL are most stable?

[mikeyakame]

If Vcore is too low you'll probably you get hard locks or BSODs with stop error 0x09.

Always run vcore a little more than you need. That way you know it wont be the cause of error when fine tuning. Little more Vcore doesn't hurt to keep as a safe buffer anyway. At least that way GTLs are easier to fine tune. You coarse tune GTLs with Vtt by setting them roughly as Cryptik said. Then when the Vtt is roughly where it needs to be, you can fine tune the gtl's up or down depending on what yours needs. Longer it takes for a rounding error to appear the closer you are to nominal! If you get it right none should appear at all.

For a Q6600 I setup on a P5Q Deluxe, For 470Mhz FSB I found 0.635 and 0.655 for CPU and 0.645 for NB at 1.26V Vtt, and 1.34V Vnb with Margin Enhancement set to Performance I think? It's been a while so don't take this for gospel.

[Ghostleader]

Thank you again CryptiK and mikeyakame for your time, much apprecieted, keep up the good work.

[Brama]

You coarse tune GTLs with Vtt by setting them roughly as Cryptik said.

Sorry but I am not able to find in the thread the Vtt value from which starting to tune.

What are roughly the rules for a dual core, X48 chipset (Asus Rampage Formula) and 4 sticks of 1 Gb memory?

Thanks,

[mikeyakame]

start with a Vtt 0.02-0.04v above Vcore or so, set the NB ref to 0.63x, CPU ref to 0.65x, and Vnb will vary depending on strap, performance level and mem divider generally. From here once you get a baseline for yourself and find out what the minimum Vnb and Vcore you can work with is, lock Vnb down a step or two above minimum and setup NB ref, once you've got that merry, then CPU ref should nearly fall into place once you lock down a solid Vcore. You'll probably need to go up or down a few steps on Vtt till you find where it's most comfortable thanks to Asus minimalist gtl adjustment on the RF

[seban]

EDIT - sorry guys - CUT

[andressergio]

Hey guys

In my case seems that this chip or mobo likes negative GTLS...

I achieved to pass IBT at:

448x9 = 4032
vcore set 1,325 vcore idle 1,316
vtt 1,29
GTLS CPU +10/-50/+10/-50
pll 1,5
mems 1:1 (but tested on 1200 PL7 also pass IBT and 2500%MEMTEST)

IBT stable whenever i run it...BUT look this

450x9 = 4050
vcore set 1,325 vcore idle 1,316
vtt 1,2875
GTLS CPU +10/-45/+10/-45
pll 1,5
mems 1:1

I get it to pass IBT but today failed BSOD...then after some hours passed...again

Everytime i want to run on more VTT seems to be more unstable, also on positive GTLS BSOD comes faster
I'm kinda stuck on this, i want to start testing all over gain but really i don't know where to start on GTLS

I can also run it at 470x9 with low volts and i can play games etc...but so hard to get it stable

Cheers
Sergio

[mikeyakame]

Hey guys

In my case seems that this chip or mobo likes negative GTLS...

I achieved to pass IBT at:

448x9 = 4032
vcore set 1,325 vcore idle 1,316
vtt 1,29
GTLS CPU +10/-50/+10/-50
pll 1,5
mems 1:1 (but tested on 1200 PL7 also pass IBT and 2500%MEMTEST)

IBT stable whenever i run it...BUT look this

450x9 = 4050
vcore set 1,325 vcore idle 1,316
vtt 1,2875
GTLS CPU +10/-45/+10/-45
pll 1,5
mems 1:1

I get it to pass IBT but today failed BSOD...then after some hours passed...again

Everytime i want to run on more VTT seems to be more unstable, also on positive GTLS BSOD comes faster
I'm kinda stuck on this, i want to start testing all over gain but really i don't know where to start on GTLS

I can also run it at 470x9 with low volts and i can play games etc...but so hard to get it stable

Cheers
Sergio

Try 12:10 divider and see if its any more stable. I never had much luck with 1:1 on a P45, didn't like it all that much.

[andressergio]

Try 12:10 divider and see if its any more stable. I never had much luck with 1:1 on a P45, didn't like it all that much.

Thanks mikey i also noticed that, but i'm wondering now and i talked this with Cryptik if it's PSU related...

i have a TT toughpower 850W, but...

Cheers
Sergio

[andressergio]

Ok after getting tired of my 450x9 i decided to push it a little and for my surprise took me less to make it stable, this chip seems hunger for vcore, more VTT has no effect at all, more VTT always lead me to unstability, same if i use positive GTLS...

The Gskills are great...

[mikeyakame]

I haven't used a P45 yet that wasn't extremely anal when it came to Vtt, it either works great or it throws errors even when its only one step higher or lower. You should be able to enable DRAM static read, and I forget which skew is the lower one, cpu or nb, but for the lower one try around 400ps, higher one try around 100-200ps. Set top one first with other set to normal. Then set top to normal, and setup bottom one, then if you aren't too far off you should be able to set both to the valeus you had working and it should post without hassles. Took me an hour of failed posts to figure out how to set them up fairly quickly.

I remember the values and their relationship to menu, just not the correct skew name I used them for!

Btw very nice memory speeds there! I'm jealous Couldn't find the 9600s here in Australia when i replaced my last set of 4x1GB sticks, so had to settle for the 8800PIs instead. They don't unfortunately have a big working range, most I can get is ~ 1175mhz out of them as pushing more than 2.1v into them just throws errors, but they are rated at 1.9v 1100 5-5-5-15 and the pair I got do rated at 1.82V! I run them at 1148 5-5-5-16 1.96v works good here.

Whats the voltage you need for the 9600s?

[andressergio]

I haven't used a P45 yet that wasn't extremely anal when it came to Vtt, it either works great or it throws errors even when its only one step higher or lower. You should be able to enable DRAM static read, and I forget which skew is the lower one, cpu or nb, but for the lower one try around 400ps, higher one try around 100-200ps. Set top one first with other set to normal. Then set top to normal, and setup bottom one, then if you aren't too far off you should be able to set both to the valeus you had working and it should post without hassles. Took me an hour of failed posts to figure out how to set them up fairly quickly.

I remember the values and their relationship to menu, just not the correct skew name I used them for!

Btw very nice memory speeds there! I'm jealous Couldn't find the 9600s here in Australia when i replaced my last set of 4x1GB sticks, so had to settle for the 8800PIs instead. They don't unfortunately have a big working range, most I can get is ~ 1175mhz out of them as pushing more than 2.1v into them just throws errors, but they are rated at 1.9v 1100 5-5-5-15 and the pair I got do rated at 1.82V! I run them at 1148 5-5-5-16 1.96v works good here.

Whats the voltage you need for the 9600s?

Thanks mikey

You won't believe but in Argentina they're selling them at 249 U$S, i bough them a month ago but payed almost 300...

Thanks for your help i will keep testing but this chip likes vcore more than all
The vdimm is on the everest screen on the gadgets

Sergio

[Brama]

start with a Vtt 0.02-0.04v above Vcore or so, set the NB ref to 0.63x, CPU ref to 0.65x,

Thanks for suggestions.
I will try to find a smart spot......

[powellandy]

Thanks for some great GTL advice, regarding looking at Gflops.

My findings (specs below) - stable 20x Linpack and 8h OCCT RAM.
Used intelburntest 1.9 at max memory (4GB total - about 3300MB used) in Vista x64 - 2 cycles.

GTL GFlops (x2)
+50/+10 47.0 46.6
+30/-10 47.8 47.8
+10/-30 47.0 47.1

Auto/Auto 47.6 47.8
+20/+20 46.3 46.5
-20/-20 Refused to boot

Now using +30/-10 although it was interesting to note how close auto/auto was.

Andy

[seban]

Hey guys

In my case seems that this chip or mobo likes negative GTLS...

I achieved to pass IBT at:

448x9 = 4032
vcore set 1,325 vcore idle 1,316
vtt 1,29
GTLS CPU +10/-50/+10/-50
pll 1,5
mems 1:1 (but tested on 1200 PL7 also pass IBT and 2500%MEMTEST)

IBT stable whenever i run it...BUT look this

450x9 = 4050
vcore set 1,325 vcore idle 1,316
vtt 1,2875
GTLS CPU +10/-45/+10/-45
pll 1,5
mems 1:1

I get it to pass IBT but today failed BSOD...then after some hours passed...again

Everytime i want to run on more VTT seems to be more unstable, also on positive GTLS BSOD comes faster
I'm kinda stuck on this, i want to start testing all over gain but really i don't know where to start on GTLS

I can also run it at 470x9 with low volts and i can play games etc...but so hard to get it stable

Cheers
Sergio

Hi m8,

TBH I was in kind of similar situation beofre at the beggining of OC.

I could do no problem Linx 10 passess but blend would fail in minutes simetimes seconds, sometimes hours and also I had different resoults from day to day for same settings - the reason was simple they were not stable and I need mode volts on most of compononets.

IMHO IBT or Linx are good as finish touch and 12h blend is more reliable - but also as my own example showed even 12h blend stable + 10 linx + Pi32 did not gourntee stability (correct skews does in my case ).

I think you should go back to begginning and work your way up with P95 instead if IBT - I could also run IBT at low voltages but not blend - I am pretty sure your volts are too low for 24/7h.

But I might be wrong of course. Also it would help if you would find point at which you start to be unstable at Auto GTLs. Becouse from ther we can find some nice GTLs for your setup.

Wish you luck and try with all around higher volts and Blend test - in fact forget blend test and do Large FTT.

And about your PSU what volts you got on lines under load?

Cheers

[ci2kla]

Seems more people is interested in tuning GTLs when using Quad core processors.
I have an Q9550 what can pass IBT 10 tests with only 1.2v and I'm wondering if it's GTL / skews related? I've tried GTL0 +50mv but unfortunately the chip seems don't like the juice and hard lock my screen

[CryptiK]

You could be lucky and have one that likes whatever the GTL Refs are set to on auto on your RE, for the given Vtt. Each CPU/board is different though so its a matter of trial and error to find what it likes. Whenever you change the Vtt, you usually have to change the GTL Refs to suit. Also as you have a quad, you should be adjusting all 4 GTL Refs.

Really nice chip btw, not often you find one like that.