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

[mskvorc1]

OK I need a little help here. I'm currently running E8500 @ 3,825 GHz @ 8,5x450 @ 1,304V. GTL ref values are on auto. Mine FSB VTT is 1,18V (Everest) - 1,20V (Bios), nForce SPP 1,4V and NF200 1,2V. Without adjusting GTL ref values mine E8500 need 1,376V for 4,037 GHz. In BIOS of my board I can only setup GTL ref values in mV, can't anywhere see GTL multiplier. Downloaded GTL calculator and if I put VTT 1,18 I get values 90/50/90/50. Since I don't know english to good I got little lost in this topic so can someone please tell me is 50/90/50/90 my starting point, because I also read that 2 core processors more like negative GTL ref values...

[mikeyakame]

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

Hard lock usually means FSB wall. Only way I know of to get around this is CPU/NB clock skews and CPU differential amplitude adjustments.

[ci2kla]

Hard lock usually means FSB wall. Only way I know of to get around this is CPU/NB clock skews and CPU differential amplitude adjustments.

Not likely that a Q9550 will hit a wall @ 471...sorry I have to disagree with you
With all GTLs on auto IBT can pass 10 tests with 1.2v, 4003Mhz.
Apart from CPU GTLs, NB GTLs becomes more important as well.
For my example, E8400 need +20mv to get a certain FSB run smooth. But for Q9550 w/ RE, +70mv for vNB GTL is the sweet spot, +60 / +80 setting or add more vtt will cause IBT calculation errors that's my finding so far. Probably now the vtt is higher then vCore (1.206v VS 1.192~1.2v) maybe that explained the problem but I'm not sure...need more time and testing to find out. Will post more soon

[mikeyakame]

Not likely that a Q9550 will hit a wall @ 471...sorry I have to disagree with you
With all GTLs on auto IBT can pass 10 tests with 1.2v, 4003Mhz.
Apart from CPU GTLs, NB GTLs becomes more important as well.
For my example, E8400 need +20mv to get a certain FSB run smooth. But for Q9550 w/ RE, +70mv for vNB GTL is the sweet spot, +60 / +80 setting or add more vtt will cause IBT calculation errors that's my finding so far. Probably now the vtt is higher then vCore (1.206v VS 1.192~1.2v) maybe that explained the problem but I'm not sure...need more time and testing to find out. Will post more soon

You may disagree, but a FSB wall can mean a multitude of things. It's usually a wall that's in place due to clock signals skewing too far apart. If you have the flexibility of bios options to work around then the wall will be higher. All depends on how good you are fine tuning the settings and how fine they can be tuned. RE has a lot of flexibility so if you are stuck at 471 then it's more the fault of the guy playing with the settings than the chip itself

I hit a wall on my Q6600 at 482mhz on RF which isn't a static wall, but without skew adjustment to get around the wall it might as well be a hard wall

[spoof]

Why there isn't NB/CPU clock skew in RF 0410 BIOS? Or it's MoBo function and my P5E X48@RF doesn't have it?

I need to ask something - is VTT tight just with CPU or this voltage have something to do with the NB? I'm asking this, because i have trouble with RAM, i try it at 1130 (it's 1100 by default) and i got errors sec after starting memtest. vNB and vDIMM doesn't help, so, there reason is somewhere else.

If hardlocks are cause by fsb wall, mine is 470. Even 1mhz up and it locks in windows. So far, the only think, that helps are VTT and vNB.

[andressergio]

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

Thank you Seban, on 8,5multi this situation is different i am much more stable and with more patterns than on 9 multi

will keep on testing

Cheers
Sergio

[mikeyakame]

Why there isn't NB/CPU clock skew in RF 0410 BIOS? Or it's MoBo function and my P5E X48@RF doesn't have it?

I need to ask something - is VTT tight just with CPU or this voltage have something to do with the NB? I'm asking this, because i have trouble with RAM, i try it at 1130 (it's 1100 by default) and i got errors sec after starting memtest. vNB and vDIMM doesn't help, so, there reason is somewhere else.

If hardlocks are cause by fsb wall, mine is 470. Even 1mhz up and it locks in windows. So far, the only think, that helps are VTT and vNB.

Because Asus bios engineers too lazy to add it. It was added to P5E3 Premium and P5E64 Evo as far as I know. Rampage Extreme came with the option already there, and all P5Q bios have this too. We drew the short end of the straw it seems my friend.

Vtt and Vnb can help to a point, but from there it's clock skews and fine independant gtl adjustment which we have neither of.

Calling it a wall just simplifies the actual explanation of the problem.

From what I can make out, the "wall" itself manifests mostly from excessive skewing between independant clock waves within the scope of the MCH and CPU, which on top of becoming dirtier from jitter, external interference, ringback, etc as bus frequency, cpu frequency, cpu multiplier rises. It can be as minute as one of the clock signals for either die becomimg too dirty and slightly skewed more than the other and you will experience a "wall" or hard system locks. This is probably just a breakdown of inter-die communications or cross-bus comms, or even phase cycle timing going out of scope.

This is the simplest I can explain what appears to me to be actually happening.

I can reproduce the "fsb wall" on a P45 chipset just with cpu/nb clock skews alone and go between completely stable at high FSB on a Quad Core to near instant cpu load onset hard locks. This is the concrete proof I base my conclusions on.

[Alien Grey]

Not likely that a Q9550 will hit a wall @ 471...sorry I have to disagree with you
With all GTLs on auto IBT can pass 10 tests with 1.2v, 4003Mhz.
Apart from CPU GTLs, NB GTLs becomes more important as well.
For my example, E8400 need +20mv to get a certain FSB run smooth. But for Q9550 w/ RE, +70mv for vNB GTL is the sweet spot, +60 / +80 setting or add more vtt will cause IBT calculation errors that's my finding so far. Probably now the vtt is higher then vCore (1.206v VS 1.192~1.2v) maybe that explained the problem but I'm not sure...need more time and testing to find out. Will post more soon

And i have to disagree with you.
IBT stable means you have no problem with your CPU stability and that is basically it.
Try to run Prime95 Blend mode and stress you Graphics card and all other components on your system and see if you can do that without problems.
See my sig and you will know what i mean.

[Alien Grey]

[QUOTE=mikeyakame;3574725]Because Asus bios engineers too lazy to add it. It was added to P5E3 Premium and P5E64 Evo as far as I know. Rampage Extreme came with the option already there, and all P5Q bios have this too. We drew the short end of the straw it seems my friend.

I always thought that we paid enough to have a good board. Maybe ASUS thinks we didn't pay enough to have a good BIOS on it.

All i see are some quick fixes in the BIOS to keep the crowd happy.

At least we don't have to worry how to setup the GTL's on our board, they are as basic as they can get. Not a problem with a good quad that can run with the CPU GTL's we have in our BIOS. Big problem if one core doesn't like the voltage.

I might be wrong, but i think that most people who can't run there Quad on high FSB on our board have the problem that one or more cores doesn't like the same CPU GTL Voltage like the others.

[spoof]

...

I'm extremely thankful for this explanation on what is actually the problem. So, i'm moving soon to P45 and see what it's gonna help.

I might be wrong, but i think that most people who can't run there Quad on high FSB on our board have the problem that one or more cores doesn't like the same CPU GTL Voltage like the others.

Correct. At same FSB where i can run a little 65x and 67x is needed with higher on Prime95 Benchmark first to cores gives error after to sec. With 65x there is no problem, but further FSB rising becomes imposible. What's why DFIs are for so many people the best OC MB, because it has tons of settings and when you understand them OC i like singing :P

[ci2kla]

And i have to disagree with you.
IBT stable means you have no problem with your CPU stability and that is basically it.
Try to run Prime95 Blend mode and stress you Graphics card and all other components on your system and see if you can do that without problems.
See my sig and you will know what i mean.

Are you trying to say I have to stress everything at the same time to make sure the FSB is stable or not? I'm not sure what you mean...
Just done some extensive test. The reason why I choose IBT as the main testing tool is because it is the fastest tool to find out if the system is stable or not (of course not for 7/24). Calculation errors exists not only CPU but also can be other components related...for example...NB GTL vRef

Last Progress so far: 1.2v vCore, 1.32v VTT CPU GTLs all on auto, NB GTLs +70mv, IBT Test = Hard Lock / Reboot
With CPU GTLs slight fine tune, IBT Test 80% correctness, ORTHOS Large FFTs HARD LOCK after 1 hr 47 mins

Will start to try getting 485FSB stable after I'm off and will post up more if any progress made. Cheers

[Alien Grey]

Are you trying to say I have to stress everything at the same time to make sure the FSB is stable or not? I'm not sure what you mean...
Just done some extensive test. The reason why I choose IBT as the main testing tool is because it is the fastest tool to find out if the system is stable or not (of course not for 7/24). Calculation errors exists not only CPU but also can be other components related...for example...NB GTL vRef

Last Progress so far: 1.2v vCore, 1.32v VTT CPU GTLs all on auto, NB GTLs +70mv, IBT Test = Hard Lock / Reboot
With CPU GTLs slight fine tune, IBT Test 80% correctness, ORTHOS Large FFTs HARD LOCK after 1 hr 47 mins

Will start to try getting 485FSB stable after I'm off and will post up more if any progress made. Cheers

Yes i do. IBT is good for your CPU stability and the first step to a stable overclock.

I use 1.22V for VTT as you can see in my sig for FSB 465MHz with CPU GTL 0.63X and NB GTL 0.67X. I can get it IBT stable with 1.16V. Prime95 Large FFT's will fail within minutes with the VTT at 1.16V.
You might need a little bit more voltage on the NB to pass Prime95 Large FFT's than you use for IBT.
To find the right Memory voltage i use MemTest86+ V2.11. If i can pass MemTest86+ V2.11 without errors i have no problems at all with my Memory stability.
The reason that i stress everything on my system is to find the right VTT to keep everything stable.

This may look insane. We are at Xtreme Systems. Why not do extreme stability tests.

Try the latest BIOS for your RE. The latest one for my RF fixed the problem with the VTT. Earlier BIOSes didn't allow me to raise the VTT higher than 1.16V without losing stability in IBT.
The ASUS Tech Support fixed the problem for the RF with BIOS 0701, they released a new BIOS for the RE at the same time. The BIOSes where released a few days after they have tested a system similar like mine to find out why i couldn't raise the VTT without losing stability. I don't know what they did with that BIOS but now i can get it stable with higher VTT.

I have to wait now for my new memory to arrive to see if i can get it stable at higher FSB. The 2 X 2 Giga OCZ Reaper HPC PC2-8500 can't go over 1120MHz with 5-5-5-15 timings.

[ci2kla]

Yes i do. IBT is good for your CPU stability and the first step to a stable overclock.

I use 1.22V for VTT as you can see in my sig for FSB 465MHz with CPU GTL 0.63X and NB GTL 0.67X. I can get it IBT stable with 1.16V. Prime95 Large FFT's will fail within minutes with the VTT at 1.16V.
You might need a little bit more voltage on the NB to pass Prime95 Large FFT's than you use for IBT.
To find the right Memory voltage i use MemTest86+ V2.11. If i can pass MemTest86+ V2.11 without errors i have no problems at all with my Memory stability.
The reason that i stress everything on my system is to find the right VTT to keep everything stable.

This may look insane. We are at Xtreme Systems. Why not do extreme stability tests.

Try the latest BIOS for your RE. The latest one for my RF fixed the problem with the VTT. Earlier BIOSes didn't allow me to raise the VTT higher than 1.16V without losing stability in IBT.
The ASUS Tech Support fixed the problem for the RF with BIOS 0701, they released a new BIOS for the RE at the same time. The BIOSes where released a few days after they have tested a system similar like mine to find out why i couldn't raise the VTT without losing stability. I don't know what they did with that BIOS but now i can get it stable with higher VTT.

I have to wait now for my new memory to arrive to see if i can get it stable at higher FSB. The 2 X 2 Giga OCZ Reaper HPC PC2-8500 can't go over 1120MHz with 5-5-5-15 timings.

Thanks for the information man. Actually I was using 1003 BIOS for testing (sorry for my sig not up to date)
to pass 485 FSB is still a no-go...trial and error takes time and makes me easily lost the way

[Alien Grey]

Start from a stable overclock and work your way up in steps of 5 or 10MHz.

It took me months and a lot of BIOSes flashes to have the stable overclock that i have now. Before BIOS 0701 i couldn't pass the 460MHz and it took me a lot of time, tests and frustrations before i knew that the VTT was the problem.
The problem is every time your higher the FSB it gets harder and harder to find out where the problem is situated and what to do to get it stable.

[CryptiK]

Are you trying to say I have to stress everything at the same time to make sure the FSB is stable or not? I'm not sure what you mean...
Just done some extensive test. The reason why I choose IBT as the main testing tool is because it is the fastest tool to find out if the system is stable or not (of course not for 7/24). Calculation errors exists not only CPU but also can be other components related...for example...NB GTL vRef

Last Progress so far: 1.2v vCore, 1.32v VTT CPU GTLs all on auto, NB GTLs +70mv, IBT Test = Hard Lock / Reboot
With CPU GTLs slight fine tune, IBT Test 80% correctness, ORTHOS Large FFTs HARD LOCK after 1 hr 47 mins

Will start to try getting 485FSB stable after I'm off and will post up more if any progress made. Cheers

Give this a go and see what happens:

GTL 0 = +10mv
GTL 1 = -35mv
GTL 2 = +10mv
GTL 3 = -35mv

Also to test CPU use Small FFT's & IBT, large FFT's more tests the ram & NB. However if your cpu is quite unstable, it can still cause large FFT's to fail.

[spoof]

My CPU have FSB Wall and VTT is the only thing that helps for pushing it back. So i have this question - have VTT voltage peaks? I mean, currently in BIOS i have 1.44v, but in BIOS Hardware Monitoring VTT is 1.36v. For me, 1.36v is still safe, but is this value same all the time or while booting, restarting and under load it rise to 1.44v?

Here for 471 it need 1.42v VTT, but for 472 it needs 1.44v VTT. This is with 65x GTL vRef.

[Alien Grey]

My CPU have FSB Wall and VTT is the only thing that helps for pushing it back. So i have this question - have VTT voltage peaks? I mean, currently in BIOS i have 1.44v, but in BIOS Hardware Monitoring VTT is 1.36v. For me, 1.36v is still safe, but is this value same all the time or while booting, restarting and under load it rise to 1.44v?

Here for 471 it need 1.42v VTT, but for 472 it needs 1.44v VTT. This is with 65x GTL vRef.

My suggestion. Try CPU GTL 0.63X and NB GTL 0.67X and try to lower VTT.
This is what i'm going to use to get to 475MHz on my RF. This is Prime95 Small FFT's stable, large FFT's have to wait for the new memory.

[ci2kla]

OK After yesterday struggling I'm completely lost...BIOS issue??

I've tested the following settings with IBT @ 485FSB
1. Changing CPU 1 or 3 GTL vREF only makes things worse both -mvs and +mvs I wonder~
2. The best so far, 1.32v VTT, 1.2v vCore, CPU 0/2 GTL vREF -30mv. My chip don't like +MVs at all...

Tested Prime 95 blend Overnight (7 hrs) stable, but not IBT
vNB @ 1.57 which is rather high...

CryptiK, thanks for your suggestion first I'll try that out later and report back

[mikeyakame]

If you can't get Linpack stable enough to run at all you've probably hit a FSB wall on you board. Try adjusting CPU & NB clock skews and see if it helps any at this point. I don't know if you have CPU Differential Amplitude/Drive option? If you do adding 2-300mv should help a little.

[spoof]

Next issue here - after testing i found, that ot 471 the board is perfectly stable, no lockups. But since i tested the chipset and RAM, CPU Multiplier set to 6. After all was done i just push it to 8.5, give enought vCPU and boot. I was expecting, if something is wrong, that should be vCPU. But isntead of reboots, BSOD i get AGAIN hard lockups? Why? It's stable on FSB, but with rising of the CPU Clock it lockup?

[Alien Grey]

I think you use the wrong CPU GTL's. If i was using the wrong GTL's i would have problems to get it stable around FSB 400MHz.

I tried Mikeyakame's suggestion to use CPU GTL 0.65X and NB GTL 0.63X and higher VTT with my Q9450 on my RF board. This makes it completely unstable. Perhaps if i would use multiplier 6 instead of 8 it might be stable.

[spoof]

I think you use the wrong CPU GTL's. If i was using the wrong GTL's i would have problems to get it stable around FSB 400MHz.

I tried Mikeyakame's suggestion to use CPU GTL 0.65X and NB GTL 0.63X and higher VTT with my Q9450 on my RF board. This makes it completely unstable. Perhaps if i would use multiplier 6 instead of 8 it might be stable.

I'm using 65x, tried 63x, doesn't help. I'll try 67x, but cores 0,1 don't like that high GTLs and they fail in P95s benchmark. For the NB, only 67x help, with lower i have mass RAM performance fail.

[mikeyakame]

You can always step down a few notches on Vtt you know. Higher isn't always better, just depends on the FSB frequency. Some frequencies need a lot, others need less, then a few MHz beyond might need lot more or less. Just depends its a variable factor and all you can do is set GTLs to 1 set of multipliers, ie 0.67 and 0.63 for RF and then try raising and dropping Vtt to find a point where the failures occur after the longest period of time. Then from there try and leave Vtt and fiddle with GTLs and see if you can stabilize it, if you can't drop Vtt by 0.02, and try again, if not raise by 0.02 above your set value and try again. and so on. It's lots of trial and error mostly, but you'll get the hang of feeling what it wants after a while.

[Alien Grey]

I'm using 65x, tried 63x, doesn't help. I'll try 67x, but cores 0,1 don't like that high GTLs and they fail in P95s benchmark. For the NB, only 67x help, with lower i have mass RAM performance fail.

Try the 0.63X for CPU GTL lower the VTT to 1.24V and see what happens. You can try higher or lower CPU Voltage to see if this makes it more stable.
If that doesn't work raise the VTT one notch and try again. Each time you raise the VTT one notch you should try with higher or lower CPU Voltage.

Once you can pass 10 or 15 minutes Prime95 Small FFT's you can try to get it stable with IBT to find the the right CPU Voltage.

One question. Do you use Loadline Calibration or is it disabled in the BIOS?

I suggest not to use it with 45Nm Quads and to disable it in the BIOS. I do a lot better with it disabled and some guys at ASUS Rampage Formula find that to.

[spoof]

So, lets put everything together:
1. vCPU 1.3*v, 470FSB x 6, CPU GTL vRef 65x, 1.61 vNB GTL vRef 67x PL8, 1.40 VTT - lockup after no more than 10 minutes.
2. vCPU 1.3*v, 470FSB x 6, CPU GTL vRef 65x, 1.61 vNB GTL vRef 67x PL8, 1.42 VTT - rock stable.
3. vCPU 1.46(measured with multimeter), 470FSB x 8.5, CPU GTL vRef 65x, 1.61 vNB GTL vRef 67x PL8, 1.42 VTT - lockup, same time. => Rising vCPU, rising vNB, rising CPU GTL vRef - doesn't help.

So far, as i said before, it seams, that VTT is the critical value here. 1.42v or 1.36v as Hardware Monitoring measures is near to unsafe values. If i'm 100% sure, that 1.36v measuret in BIOS is the real value all the time, maybe i'll push it more to 1.42v real. If this isn't the case i think it's worthless even trying to find with what VTT case 3 would work. Lowering VTT under 1.36v take me to highest stable FSB at 450. With 470FSB and 1.24v VTT it won't even start to load OS. What is the most stange thing for me here is why rising just the multiplier and applying enough vCPU (1.48 vCPU doesn't help too and i ain't gonna use higher for 24/) it push me back to lockup. I thought that max CPU FSB ot max CPU freq are two separate things.