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[SOLVED] Q9550 @ 3.8GHz failing Prime95 Large FFTs - Page 2

post #11 of 38
Thread Starter 
Quote:
Originally Posted by Mattb2e;11872669 
Your specified ram settings from the manufacturer are 2.0v-2.1v @ 5-5-5-12

I know. I lowered the timings to achieve better stability and leave the RAM out of the picture.
Quote:
Originally Posted by PanicProne;11872667 
The person who told you that is wrong.

CPU GTL Ref tuning is essential to stability with high clocks when overclocking Core 2 Quads CPUs.

CPU PLL is actually important in achieving and stabilizing higher FSBs (you will want to stay below 1.6v for safety reasons).

LLC Is perfectly safe to have enabled if you are using low Vcore and a high quality board. Which is your case.

It won't kill RAM slots lol, don't worry about it. Where do you get this misinformation?

You have one of the best P45 motherboards in existence, it can take all sorts of abuse.

Trust me, I've had a P5Q board before and a Q9550.

Read it on one the XS forums. lol! With LLC enabled, I can leave my vcore at 1.21875v so I might try that. The problem really is FSB Term and NB voltage. OC keeps failing Large FFT frown.gif I can even run IBT 5x maximum and it would be stable but keeps failing large FFT!! DAMN YOU LARGE FFT!!! mad.gif
post #12 of 38
Quote:
Originally Posted by PanicProne View Post
The person who told you that is wrong.

CPU GTL Ref tuning is essential to stability with high clocks when overclocking Core 2 Quads CPUs.

CPU PLL is actually important in achieving and stabilizing higher FSBs (you will want to stay below 1.6v for safety reasons).

LLC Is perfectly safe to have enabled if you are using low Vcore and a high quality board. Which is your case.

It won't kill RAM slots lol, don't worry about it. Where do you get this misinformation?

You have one of the best P45 motherboards in existence, it can take all sorts of abuse.

Trust me, I've had a P5Q board before and a Q9550.
QFT. GTLrefs are very important at high clocks, it just takes alot of time and determination to find the right settings.

LLC is a potential danger if you run it at high Vcore, but at 1.3v I dont see it being much of an issue. What it does is it will allow voltage spikes between load and idle transitions, bad if your close to the limit, which you are not.

Follow panicprone's suggestions, his settings look like a solid start.
post #13 of 38
If you've been reading XS forums, then you must also know that a right balance between VTT and CPU GTLs is essential.

VTT is multiplied by GTLs multi to achieve a total reference voltage of around 0.8v.

1.20v * .63x = 0.756v

Try to increase VTT to 1.26 and keep the GTLs @ .63x
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post #14 of 38
Quote:
Originally Posted by PanicProne View Post
If you've been reading XS forums, then you must also know that a right balance between VTT and CPU GTLs is essential.

VTT is multiplied by GTLs multi to achieve a total reference voltage of around 0.8v.

1.20v * .63x = 0.756v

Try to increase VTT to 1.26 and keep the GTLs @ .63x
I never had a concrete understanding of what the desired voltage was, is .8v a static value, or does it change as your clock is increased?

That really was the only thing holding me back from achieving 4.0ghz myself.
post #15 of 38
Quote:
Originally Posted by Mattb2e View Post
I never had a concrete understanding of what the desired voltage was, is .8v a static value, or does it change as your clock is increased?

That really was the only thing holding me back from achieving 4.0ghz myself.
I think what happens is that when you increase clocks and then raise the VTT to compensate for the higher FSB, you actually break the balance between VTT and GTL refs, and so that's why they are adjustable, so you can try to reach for the same reference voltage of 0.8v with higher (or lower) VTT.


0.8v I believe is Intel's spec for the desired reference voltage. In the end, the final FSB voltage is the result of VTT * CPU GTL Refs.
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post #16 of 38
Thread Starter 
Quote:
Originally Posted by PanicProne View Post
If you've been reading XS forums, then you must also know that a right balance between VTT and CPU GTLs is essential.

VTT is multiplied by GTLs multi to achieve a total reference voltage of around 0.8v.

1.20v * .63x = 0.756v

Try to increase VTT to 1.26 and keep the GTLs @ .63x
Here are my settings so far:
CPU Ratio Setting: 8.5
FSB Frequency: 450 MHz
FSB Strap to North Bridge: AUTO
DRAM Frequency: 900 MHz
DRAM Timings: 5-5-5-18-50

CPU Voltage: 1.21875v
CPU GTL Voltage Reference (0/2): 0.63
CPU GTL Voltage Reference (0/2): 0.63

CPU PLL Voltage: 1.54v
FSB Termination Voltage: 1.26v
DRAM Voltage: 2.0v
NB Voltage: 1.30v
NB GTL Reference: 0.670

Load-Line Calibration: Enabled

And... it won't boot to windows I have AHCI as my system configuration, would it help if I changed it back to IDE?
post #17 of 38
Quote:
Originally Posted by PanicProne View Post
The person who told you that is wrong.

CPU GTL Ref tuning is essential to stability with high clocks when overclocking Core 2 Quads CPUs.

CPU PLL is actually important in achieving and stabilizing higher FSBs (you will want to stay below 1.6v for safety reasons).

LLC Is perfectly safe to have enabled if you are using low Vcore and a high quality board. Which is your case.

It won't kill RAM slots lol, don't worry about it. Where do you get this misinformation?

You have one of the best P45 motherboards in existence, it can take all sorts of abuse.

Trust me, I've had a P5Q board before and a Q9550.
Follow This Man.

Overclocking 45nm Core 2 Quads with High FSB was one of the harder overclocks I've ever done. A 475x8.5 overclock is pretty difficult to say the least, because the GTL's may need to be tweaked and tweaked relative to VTT.
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post #18 of 38
Quote:
Originally Posted by pipnasty View Post
Here are my settings so far:
CPU Ratio Setting: 8.5
FSB Frequency: 450 MHz
FSB Strap to North Bridge: AUTO
DRAM Frequency: 900 MHz
DRAM Timings: 5-5-5-18-50

CPU Voltage: 1.21875v
CPU GTL Voltage Reference (0/2): 0.63
CPU GTL Voltage Reference (0/2): 0.63

CPU PLL Voltage: 1.54v
FSB Termination Voltage: 1.26v
DRAM Voltage: 2.0v
NB Voltage: 1.30v
NB GTL Reference: 0.670

Load-Line Calibration: Enabled

And... it won't boot to windows I have AHCI as my system configuration, would it help if I changed it back to IDE?
Man, your Vcore is too low! for that clock speed! 1.21v? You would need a really golden chip for that.

Get it to 1.3v just to be on the safe side and rule out Vcore. KEEP LLC ENABLED.
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post #19 of 38
Thread Starter 
Quote:
Originally Posted by PanicProne View Post
Man, your Vcore is too low! for that clock speed! 1.21v? You would need a really golden chip for that.

Get it to 1.3v just to be on the safe side and rule out Vcore. KEEP LLC ENABLED.
Yup, I tried 1.30v for vcore. Got BSOD when I entered windows. LLC still enabled. I think FSB term is causing this instability because I upped it to 1.26v. Based from previous overclocking, raising it above 1.20v causes instability. I can't understand it.. damn frustrating
post #20 of 38
Quote:
Originally Posted by pipnasty View Post
Yup, I tried 1.30v for vcore. Got BSOD when I entered windows. LLC still enabled. I think FSB term is causing this instability because I upped it to 1.26v. Based from previous overclocking, raising it above 1.20v causes instability. I can't understand it.. damn frustrating
I hardly think VTT is the cause of instabilty. But if you think so, then lower it back to 1.20v and play with the CPU GTLs.

You could also try to put RAM @ 2.1v just to rule it out.

But before that, run Prime 95 and see which core(s) actually fail, and then adjust CPU GTL accordingly.

If core 0 or 2 fails, adjust CPU GTL ref 0/2.

If core 1 or 3 fails, adjust CPU GTL ref 1/3.

If it doesn't work, you'll have to increase VTT again. And then, calibrate the GTLs once again.

It won't be easy.

In case you didn't know, a Core 2 Quad is two separate dual core dies in a single package, so these pairs of cores communicate externally through the FSB.
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