Q9550 + EP45-UD3P, need help hitting 4 Ghz please

[Zach_]

Hey guys,

This is my setup:

Processor: Q9550 @ 3.8 GHz
Mainboard: GA-EP45-UD3P
Memory: G.Skill DDR2-1066 PI 4GB

Currently I have my system running at 3.8 GHz, these are my BIOS settings, I've highlighted the settings I changed:

Robust Graphics Booster [Auto]
CPU Clock Ratio[8]
Fine CPU Clock Ratio [.5]

**********Clock Chip Control*************************

CPU Host Clock Control [Enable]
CPU Host Frequency (Mhz) [450]
PCI Express Frequency (Mhz) [100]
C.I.A 2 [Disable]

*********Advanced Clock Control**********************

CPU Clock Drive [700mV]
PCI Express Clock Drive [700mV]
CPU Clock Skew [0ps]
MCH Clock Skew [0ps]

**********DRAM Performance Control***********

Performance Enhance [Standard]
Extreme Memory Profile (XMP) [Auto]
(G) MCH Frequency Latch [400]
System Memory Multipler [2.00D]
Memory Frequency [900]
DRAM Timing Selectable [Manual]

CAS Latency Time [5]
tRCD [5]
tRP [5]
tRAS [15]

*******Advanced Timing Control***********

tRRD [Auto]
tWTR [Auto]
tWR [Auto]
tRFC [Auto]
tRTP [Auto]
Command Rate (cmd) [Auto/Default]


***********Motherboard Voltage Control*******

Load-Line Calibration [Enabled]
CPU Vcore [1.2500] -> [1.4000]
CPU Termination [1.2000] -> [1.320]
CPU PLL [1.500] (Normal)
CPU Reference [0.760] (Normal)

MCH Core [1.2000] -> [1.3400]
MCH Reference [0.760] (Normal)
MCH/DRAM Refernce [0.900] (Normal)
ICH I/O [1.500] (Normal)
ICH Core [1.100] (Normal)

DRAM Voltage [2.1000]
DRAM Termination [Auto]
Channel A Ref [Auto]
Channel B Ref [Auto]

This seems to be pretty stable at the moment, it passed 25 cycles of Intel Burn Test at Maximum stress level and 8 hours of Blend test in Prime95, however, Core #4 stopped working after 8 hours and 40 minutes with an error on Prime95 as follows:

"Rounding was 0.5, expected 0.4 or less"

Since it passed 25 cycles on IBT I'm pretty sure that the CPU is stable, whatever stopped Prime95 must be related to the RAM.

Anyway, I am aiming to hit 4 GHz, I tried it before but only managed to hit it with a Vcore of 1.4375 or 1.45, I was told that chip degradation is likely to occur when using these voltages so I am trying to hit a more reasonable Vcore.

Also I've seen many people doing 4 GHz with Q9550 and EP45-UD3P on much lowe voltages.

What do you think about the current Overclock and how should I proceed if I want to reach 4 GHz?

A response from LSD would be really helpful.

Thanks in advance, Zach ;)

[Chike]

Re: Q9550 + EP45-UD3P, need help hitting 4 Ghz please

Clocks drive 700 show you haven't began with optimized defaults, it is recommended to begin with optimized defaults.
What are GFlops at 3.8GHz with 3072MB?
Leave references auto not normal, they need to scale with VTT(CPU Termination)/DRAM Voltage.
MCH and CPU references may need some tweaking, also Clock skews.

[Zach_]

Re: Q9550 + EP45-UD3P, need help hitting 4 Ghz please

Hey Chike, thanks for the reply,

IBT allows me to test with 2887MB of memory, that's the max, for 25 cycles the GFlops are varying from 49.5-50 and every cycle takes about 90 seconds to run.

I've loaded the Optimized Defaults (And of course disabled C1E, C2/C2E and EIST off) and this is where I'm at now:

Robust Graphics Booster [Auto]
CPU Clock Ratio[8]
Fine CPU Clock Ratio [.5]
CPU Frequency 3.82GHz (450x8.5)

**********Clock Chip Control*************************

CPU Host Clock Control [Enable]
CPU Host Frequency (Mhz) [450]
PCI Express Frequency (Mhz) [100]
C.I.A 2 [Disable]

*********Advanced Clock Control**********************

CPU Clock Drive [700mV] -> [800mV]
PCI Express Clock Drive [700mV] -> [900mV]
CPU Clock Skew [0ps]
MCH Clock Skew [0ps]

**********DRAM Performance Control***********

Performance Enhance [Standard]
Extreme Memory Profile (XMP) [Auto]
(G) MCH Frequency Latch [400]
System Memory Multipler [2.00D]
Memory Frequency [900]
DRAM Timing Selectable [Manual]

CAS Latency Time [5]
tRCD [5]
tRP [5]
tRAS [15]

*******Advanced Timing Control***********

tRRD [Auto]
tWTR [Auto]
tWR [Auto]
tRFC [Auto]
tRTP [Auto]
Command Rate (cmd) [Auto/Default]


***********Motherboard Voltage Control*******

Load-Line Calibration [Enabled]
CPU Vcore [1.2500] -> [1.4000]
CPU Termination [1.2000] -> [1.320]
CPU PLL [1.500] (Hard Set)
CPU Reference [0.760] (Auto)

MCH Core [1.1000] -> [1.3400]
MCH Reference [0.760] (Auto)
MCH/DRAM Refernce [0.900] (Auto)
ICH I/O [1.500] (Auto)
ICH Core [1.100] (Auto)

DRAM Voltage [2.1000]
DRAM Termination [Auto]
Channel A Ref [Auto]
Channel B Ref [Auto]

Couple of questions:

1. Which references should be set to Auto and which to Normal? Currently I changed it after your post to this:

Load-Line Calibration [Enabled]
CPU Vcore [1.2500] -> [1.4000]
CPU Termination [1.2000] -> [1.320]
CPU PLL [1.500] (Hard set)
CPU Reference [0.760] (Auto)

MCH Core [1.1000] -> [1.3400]
MCH Reference [0.760] (Auto)
MCH/DRAM Refernce [0.900] (Auto)
ICH I/O [1.500] (Auto)
ICH Core [1.100] (Auto)

Is that OK?

2. Which tweaks would you recommend to change in order to hit 4 GHz without raising Vcore too much? Please give me a setting I can use to test this at.

[Chike]

Re: Q9550 + EP45-UD3P, need help hitting 4 Ghz please

Yes, the problem is most likely related to RAM/FSB.
At 448x8.5 I only need 1.22v VTT and 1.18v/1.2v MCH Core.
The key to high frequency FSB on the P45 boards are MCH/CPU references, and sometimes the clock skews.
The references are percent of VTT and their value change with it, default is 63.33% VTT (0.76 @ 1.2v VTT).
To be sure of their value without the need for doing math, always change thos with VTT set to 1.2v as follow:
1. Change VTT to 1.2v
2. Change the reference value to the desired value.
3. Change VTT back to it's original value.

Always change one option(VTT, or MCH Reference, or CPU Reference) at a time or there is no way to tell which was the one that made difference.
MCH Reference useually need to be set below default value (mine is 0.72v @ 1.2v VTT) but sometimes avove default.
CPU Reference may be either way, above default useually for quad cores.

Only one of the clock skews(not absolute sure about this) will need a change (if at all). I use 150ps CPU Clock Skew.

Remember the FFT that fail Prime95, you can then run only this FFT to reproduce the error. Select blend then custom, enter the failing FFT size in both min and max FFT and run.

Try to find the right references for the lowest possible MCH Core and VTT.

EDIT: almost forgot, set CPU PLL 1.55-1.59v, begin with one click above default.

[Zach_]

Re: Q9550 + EP45-UD3P, need help hitting 4 Ghz please

Hey Chike,

First off, thanks for your tips, they are the most professional I've heard yet.

I just have a couple of questions because I wanna make sure I'm doing it right before I change settings.

1. VTT is CPU Termination right? and I should set CPU Reference to 63.33% from that right? So if I'm now at 1.32 I should set CPU Ref to 0.835 approximately correct? Also, should I try a lower VTT or is it tweaked well currently?

2. MCH reference should be changed with respect to MCH Core right? So if I'm now at 1.34 MCH Core, I should set MCH Ref to 63.33% of that, or lower from the default like you said? Is my MCH core set too high? Should it be lowered?

3. About this:

"To be sure of their value without the need for doing math, always change thos with VTT set to 1.2v as follow:
1. Change VTT to 1.2v
2. Change the reference value to the desired value.
3. Change VTT back to it's original value."

I'm not sure I understand how to make the change, can you give an example please?

4. Before I try to test 4 GHz, which voltages would you tweak and what is the absolute maximum Vcore I should reach with the Q9550?

5. About PLL, my BIOS lets me jump directly to 1.57 from 1.50, there is no mid range for that, I read somewhere that raising PLL to 1.57 which is the maximum could seriously be risky for the CPU, however, if you tell me that its perfectly safe, I'll go ahead and make the change.

6. I read a bit about Clock Skews and it says that they can provide stability when overclocking, to what should I change this value in order to try and get to 4 GHz?

Sorry I have so many questions I'm just trying to do this right.

Thanks

[Chike]

Re: Q9550 + EP45-UD3P, need help hitting 4 Ghz please

Both MCH Reference and CPU Reference are relative to VTT, not MCH Core or vcore. However due to the way FSB is implemented lowering VTT may help lowering vcore or MCH Core.
With your current 1.32v VTT,
1. Set VTT to 1.2v.
2. Set MCH Reference to 0.76v
3. Set VTT 1.32v, MCH Reference will scale with VTT.

Auto set thereference to 63.33% (0.76v @ 1.2v VTT) so no point testing this. Try 0.74, 0.72, 0.70, 0.68 while it make the system more stable. If it makes it worse try 0.80, 0.84, 0.88. All those @ 1.2 VTT ofcourse.

Try to make those changes with 471MHz FSB and CPU Ratio x8. vcore should be enough since you are below current CPU frequency and FSB less stable which may help in finding the right settings.
After you find more stable reference you may try to lower VTT or MCH Core.

For safe and absolute min/max voltage values see:



EDIT: if you wish to read more about references: Understanding GTL Reference Voltage

[Zach_]

Re: Q9550 + EP45-UD3P, need help hitting 4 Ghz please

1. Ok so both References are with respect to CPU Termination, if I understand you correctly, I should lower VTT back to 1.200 and then try to raise both CPU and MCH reference to try and find stability right?

2. Did you mean 471*8.5? 471*8 is still 3.8 GHz...

[Chike]

Re: Q9550 + EP45-UD3P, need help hitting 4 Ghz please

Both with respect to VTT, lower VTT to 1.2 to make the change then restore to 1.32.

Yes 471x8 because we want to stabilise the FSB/memory without adding "noise" of higher CPU frequency.

[Zach_]

Re: Q9550 + EP45-UD3P, need help hitting 4 Ghz please

Gotcha, thanks I am going to try this today and get back to you with results. Hopefully the system will be fully stable at 3.8 GHz and we can move to 4 GHz from there.

[Chike]

Re: Q9550 + EP45-UD3P, need help hitting 4 Ghz please

Yup if it can do it, I can't get my system stable at much over 450MHz no matter what I do and need a lot of voltage and high temps to go over 3.8GHz so I leave it at that.

[Zach_]

Re: Q9550 + EP45-UD3P, need help hitting 4 Ghz please

Just one last question about the References,

I should set VTT to 1.2, change MCH and CPU references, test IBT/Prime95 and if stable, restore VTT to 1.32, correct?

[Chike]

Re: Q9550 + EP45-UD3P, need help hitting 4 Ghz please

no for current settings:
set vtt 1.2
change MCH or CPU reference (only one of them at a time)
restore 1.32 vtt
save, reboot, with prime95 (or memtest86+ first)..

begin with MCH reference, it most likely need to be tweaked, then CPU reference.

[Zach_]

Re: Q9550 + EP45-UD3P, need help hitting 4 Ghz please

Thanks for clarifying that, I'll get back to you with results :)

[Zach_]

Re: Q9550 + EP45-UD3P, need help hitting 4 Ghz please

Ok Chike, update:

I set the FSB to 475 and the multiplier to 8 = 3800 MHz exactly and set the following voltages:

***********Motherboard Voltage Control*******

Load-Line Calibration [Enabled]
CPU Vcore [1.2500] -> [1.4000]
CPU Termination [1.2000] -> [1.320]
CPU PLL [1.500] -> [1.5700]
CPU Reference [0.760]

MCH Core [1.2000] -> [1.3400]
MCH Reference [0.760] -> [0.8400]
MCH/DRAM Refernce [0.900]
ICH I/O [1.500]
ICH Core [1.100]

DRAM Voltage [2.1000]
DRAM Termination [Auto]
Channel A Ref [Auto]
Channel B Ref [Auto]

Everything else on Auto.

I ran memtest86+ for 3 full passes, the test took exactly 2 hours to complete and was stable. Then I ran IBT for 10 passes at maximum stress with 33.5-34 GFlops and every pass was completed in 130 seconds.

So at this time it looks like the RAM is stable at 475 FSB and the CPU as well.

Now I want to move on to 471*8.5, what would you say should be the next step?

Can I manage 4 GHz with a Vcore lower than 1.4 if I raised PLL to 1.57 and MCH Reference to 0.840? Will that compensate for a lower Vcore?

[Chike]

Re: Q9550 + EP45-UD3P, need help hitting 4 Ghz please

Those GFlops are not even close to what they should be. How much memory was used?
Try to repeat tests with the same amount of memory, 3072MB if you can, and for 64bit OS LinX is better.
GFlops at 3800 should be 50+.
I can't make what CPU reference is, is it at .760 absolute value? Please list the value for 1.2v e.g.:
MCH Reference [0.8400] ; (0.76 @ 1.2v VTT)
or just
MCH Reference [0.76 @ 1.2v VTT]
The absolute value is not so important.

As I said before there is no point of testing 0.76 @ 1.2v VTT as this is what auto sets.
I migrated the settings I have found stable at high OC to all my OC profiles and it seems they are holding fine, even if not absolutely nesessarry.

I need 1.4v vcore with LLC enabled for 3.8GHz I don't know about your chip, maybe you can get away with less, but we need to try to lower VTT first.

One last thing, set tRD(Static tRead Value in BIOS, Performance Level in MemSet) 10 or 11, for both chabbels for now, later you can try to lower it. Auto sets it too high or disables it altogether.