Sandy Bridge - My findings regarding memory and the processor

[SimonMaltby]

My Sandy Bridge setup has been one of the most successful I have seen on the forum and I spent some time this weekend trying to work out why and where my limitations are.

I currently have my setup able to achieve the following:

1. 5.4GHz - Stable enough to benchmark, but not run prime95
2. 5.0Ghz - Prime95 stable (1.4v)
3. 4.8GHz - Fully stable at 1.35v - so probable 24/7 setup

I am using the Asus P8P67 Pro motherboard and a 2600K processor.

Firstly, my CPU hits a wall at 4.8GHz without the 1053 bios and the CPU PLL Overvoltage set to enabled. Then overclocking to 5.4GHz relies on Vcore and very minor tweaks to PLL voltage. Nothing else in the bios including LLC seems to make any real difference.

What is really interesting are my findings regarding RAM.
I have two sets of RAM, but have only achieved 5GHz + on the CPU using one of those sets and more interestingly that set at a single ratio and timings.

When my OCZ 1600 6-8-6-24 1T @ 1.425v ram is used with the bios manually set to 1600MHz, Vdimm set to 1.425 and timings set as stated overclocking to 5.4GHz seems very easy. I cant get anywhere at 100x55, 100x54 is the max.

My ram passes 3 passes of memtest at 1866MHz 6-8-6-24 1T at 1.575v but at the 1866ram ratio stability when overclocking the CPU above 5GHz disappears.

What is more interesting is that I get instability at any overclock above 4.5Ghz if I alter almost any RAM settings. Most notably even changing the ratio down to 1333, 1066 or even 800 with all the other settings fixed as above I get massive instability, often resulting in the board even booting.

Using my other set of RAM, Patriot 2400 9-11-9-27 1T @1.65v I get no real stability when overclocking. I also suffer the cold boot issue discussed on the board and also suffered the RED Ram light when first changing the ram resulting in needing to start with one stick, set the Bios manually and then add the second stick.

So my conclusion is that the CPU stability, at least for me and using the Asus P8P67 motherboard, is very dependent upon the RAM ratio and settings. This maybe because the Motherboard is setting other RAM timings behind the scenes badly or it maybe that the CPU memory controller is very fussy.

Anyway, for anyone struggling to overclock or get stability with their Sandy Bridge I recommend the following...

• Enable CPU PLL Overclocking in the Bios.
• Try your ram at different Speeds - You may need to find the sweet spot for the relationship between your CPU and Ram.

Hope this helps.

UPDATE: 18 JAN 2011
I have been looking into my findings some more and have now discovered that I can get stability with my OCZ ram at 1866MHz
The Asus board has a massive amount of memory settings in addition to the standard CAS etc. I have made a note of these settings at 1600MHz and applied them manually at 1866MHz.
When I did this first time, I manually set them all... I have now discovered that there are a few that make the system very unstable.

With the Ram settings manually set I now have as much stability as I did at 1600MHz

So in line with my findings yesterday, I can confirm that it is the Ram settings that the Asus board chooses that makes things less stable.

My next step is to explore these settings further and see if I can find which aid or reduce stability.

 

[SimonMaltby]

Thanks for your work Simon - how are you setting all your other voltages? (VCCSA, VCCIO, CPU PLL).

I'm always unsure what to do with these. People seem to tend to post only their Vcore/ram - is it an assumption that the rest should be on auto? Isn't that asking for trouble if the board tries to ramp them up too far?

I'm running an i5 2500K, 8GB Corsair Vengeance 8-8-8-24 @ 1.5V, P8P67 Pro. Currently stable at 4.4, but I want more out of it (4.6 minimum really).

My current settings are:

Load Line Calibration: Extreme
VRM Frequency: Auto
VRM Spread Spectrum: Disabled
Phase Control: Standard
Duty Control: T. Probe

CPU Voltage - 1.30
DRAM Voltage - 1.50
VCCSA Voltage -0.92500
VCCIO Voltage - 1.05000
CPU PLL Voltage - 1.80
PCH Voltage - Auto
CPU Spread Spectrum - Auto

I'm running BIOS 1201, so don't have access to the enable CPU PLL overclocking setting yet.

I've tried 4.5GHz at 1.32 vcore, and the above settings, but it BSOD'd after a while in prime.

Do you have any pointers? Thanks.

I don't recognise BIOS 1201?
I found that everything on AUTO voltage wise to get to 4.8GHz (but i'm 2600K not 2500K). I only needed to increase voltages other than vcore over 4.8GHz.

For best results I set this
MULTI - AUTO
LLC - AUTO

CPU PLL Overvoltage: ENABLED (Must have for over 4.8 for me will be less for 2500K)

CPU Voltage - 1.185v
DRAM Voltage - 1.425 (but this is based on your own ram)
VCCSA Voltage -AUTO
VCCIO Voltage - AUTO (Causes me instability if changed)
CPU PLL Voltage - AUTO
PCH Voltage - Auto
CPU Spread Spectrum - Auto

I then use the Asus windows software to do the overclock
Just step up the vcore and the Multi and run prime95 at each step... I found if it passed 15 minutes prime it is there or thereabouts ok.

I have only altered Vcore, VCCSA (+ 2 clicks) and CPU PLL (+3 clicks) for 5GHz.

I advise changing voltages then apply... then change the Turbo multi and apply again.

 

[SimonMaltby]

That is really interesting, I have heard others say simalar things and wonder if it is only with UEFI bios based motherboard that this problem is happening.

From my point of view I am not having any ram issues at all. My CPU walls (hard wall) at 5.288GHz regardless of cooling method.

I have run my Geil ram at 2133MHz at that CPU frequency. WPrime 1024 stable, and all 3D benchmarks run perfectly including 3DMarkVantage performance - and that surprised me.

With my EVO2 ram I can run 6-9-6-23 again for all benchmarks at 1866 right up to 1998 not willing to set my BLCK above 1060 to achieve a higher ram frequency. I have to juggle my settings to stay this side of 5.288 even one MHz over and no boot to windows at all.

Same with my Corsair GT ram 8-9-8-24 on XMP profile all day long. Have not tested with a new kit of GT ram 7-8-7 yet... but hope to do some soon.

Basically no problems what so ever from day one with my set up.

Gigabyte UD7 running F7a offical bios.

Settings are pretty much the same as yours. Except I drop my Pll just a tab below the auto settings.

Have to say it does feel, from the Asus P8P67 issues as if the Asus does some RAM stuff that we can't see and it maybe that causing issues.

I find your comment interesting about a CPU Hard Wall... I'm similar at 5.4GHz, if i touch BCLK (up or down) or try and apply 100x55 I get nowhere. Once I overcame the wall at 4.8GHz every increase in multiplier had some kind of stability, meaning that it changed to it but only lasted a short while before BSOD if the voltage was not high enough. 55 multi is different and just causes the screen to freeze. I'm not a believer in 'Hard Wall', I think there is always something that can be done to get further. That said, I have now stopped trying. I'm quite happy with some killer benchmarks at 5.4 and the ability to do anything at 5GHz, if i choose to. Last night I wiped the hard drive and have put on Raid 0 and installed a nice clean XP Pro x64 and Windows 7 Ultimate x64 - Tonight i will actually put on some games and start using the thing LOL

 

[SimonMaltby]

Sorry, that was me being dim and reading the wrong number - it was whatever the board came with basically. I've flashed to 1053 now.



Thanks for that. I assume it's safe therefore to leave them all on AUTO? Apart from CPU/DRAM obviously.

What about all these settings?

VRM Frequency
VRM Spread Spectrum
Phase Control
Duty Control

I started setting those to EXTREME, but have now tested and found that AUTO / DEFAULT made no difference to my stability so they are back their default settings.

 

[SimonMaltby]

One CPU just blew past 55x multi and was snatched out of my rig before I could even react. And he calls himself a mate.

Give me his address and I will go sort him out... oh and steal his chip of course LOL

 

[SimonMaltby]

Im using this ram http://www.overclockers.co.uk/showproduct.php?prodid=MY-292-CS&groupid=701&catid=8&subcat=1387 and it wont run prim stable at 1866 no matter what the cpu is set to default or overclock.

Enable CPU PLL Overclocking in the Bios i just tried this with ram set to 1866 and it wouldn't boot had to hold down button on the mobo to reset the ram so have now turned it back to auto and my ram to 1600.

And with the RAM at 1600 and PLL Overclocking?

 

[SimonMaltby]

Just enabled it and its booted into windows ok with ram set to 1600 ill run prime and report back.My ram is not on the qvl list in the manual and if i select xmp it sets the timings wrong so i set it all manually.

My Patriot is on the QVL and it does not work well at all... my OCZ is not on the list and works brilliantly but only at 1600

 

[SimonMaltby]

It's BSOD'ing in P95 at 4.5GHz:

Internal PLL Overvoltage: Enabled

Load Line Calibration: Extreme
VRM Frequency: Auto
VRM Spread Spectrum: Disabled
Phase Control: Standard
Duty Control: T. Probe

CPU Voltage - 1.32v
DRAM Voltage - 1.5
VCCSA Voltage -AUTO
VCCIO Voltage - AUTO
CPU PLL Voltage - AUTO
PCH Voltage - AUTO
CPU Spread Spectrum - AUTO

What options do I have other than just upping Vcore? With LLC on it's pushing 1.34V in CPU-Z

Have you...
a) tested you ram using memtest4.2 via a bootCD
b) Try setting LLC to auto rather than EXTREME
c) VRM Spread Spectrum: disabled.... not by my machine, but is there not an Auto?

Here is what I did have set for 5GHz... but as I say i switched most back to Auto.

 

[SimonMaltby]

It BSOD's even earlier with LLC auto.

VRM Spread Spectrum is either disabled or enabled.

Also, the last few times I've made changes in BIOS (or after a BSOD), I've had to go through the following:

Save BIOS settings (or after BSOD).
It turns itself off, then turns on again.
Blank screen.
I turn it off, then turn it on again.
It turns itself off, then turns on again.
I get the Overclocking Failed message.
I turn it off, then turn it on again.
It turns itself off, then turns on again.
Then I get into windows.

I take it that's not normal behaviour

I get this a lot when altering things, but it is normally when the RAM is not working in sync very well.

 

[SimonMaltby]

I have been looking into my findings some more and have now discovered that I can get stability with my OCZ ram at 1866MHz
The Asus board has a massive amount of memory settings in addition to the standard CAS etc. I have made a note of these settings at 1600MHz and applied them manually at 1866MHz.
When I did this first time, I manually set them all... I have now discovered that there are a few that make the system very unstable.

With the Ram settings manually set I now have as much stability as I did at 1600MHz

So in line with my findings yesterday, I can confirm that it is the Ram settings that the Asus board chooses that makes things less stable.

My next step is to explore these settings further and see if I can find which aid or reduce stability.

 

[SimonMaltby]

It does seem strange i can benchmark ok and system runs fine with ram at 1866 but it wont cold boot with any setting over 1333

Based on my results try writing down the second and third ram settings that the board selects when booted at 1333MHz and then enter them manually before switching back to 1600 or even 1866. Will put up some photos of my settings in a minute... the only setting I must not manually set is DRAM RTL(CHA) and DRAM RTL(CHB). Fixing this causes no boot.

Just to clarify..
With all these on Auto at 1600Mhz Ram - I can get to 5.4Ghz
With all these on Auto at 1866Mhz Ram - Over clock starts to fail above 4.8GHz (Bios sets these to Higher Values)
With these manual settings at 1866MHz Ram - I can over clock to 5.4GHz again

So actually fixing to lower values at higher speed makes it more stable! I'm guessing, yet to try, that these are just sweet spot settings because booting at 1333MHz will reduce these and that causes more instability than 1866MHz.

 

[SimonMaltby]

Doing this has fixed it http://vip.asus.com/forum/view.aspx...d_id=1&model=P8P67+PRO&page=1&SLanguage=en-us now it cold boots fine using the xmp settings and 1866.

I suspect that the reset has re-worked all the ram settings. I suspect as you go messing about, particularly with BLCK or RAM speed these will get messed up again. Could you take a note of the secondary timings from the Bios and then next time the system starts playing up compare them again to see if the bios has changed them.

 

[SimonMaltby]

I wish you hadn't asked me to do that lol.

Sorry.... you should not have saved when exiting... just switched off or exit without saving.

When you manually entered the secondary timings... did you leave the two DRAM RTL's on AUTO?
Also, now you have it working again.... are the settings the same as you wrote down?

 

[SimonMaltby]

But i didnt change any settings it just screwed up all on its own.

It just cold booted ok by the way.

Well that's just weird then.

 

[SimonMaltby]

when i wrote them down they were all set to auto i didn't make any changes just saved and exit and then it wouldn't boot when i went into the bios the values had changed but were still on auto and even when i wrote them in to what they were before it still wouldn't boot..

Should i buy some different ram or a different mobo or hope asus fix it with a new bios im not sure but its very fussy and starting to annoy me now.

Can you post the settings you wrote down please?

 

[SimonMaltby]

I wish i wrote the 3rd timings down aswell while i was at it but im scared to go back in in case it screws up again lol.

Thanks... Going back in should be fine so long as you don't save... clearly even if you have not made any changes. Just leave without saving and it should be fine.

 

[SimonMaltby]

Ok so a bit more work on this tonight has yielded the following...

The Ram value that seems to be blocking overclocking seems to be
DRAM CKE Minimum Pulse Width: or tCKEMin (acording to google)

I can leave all the second and third ram settings on Auto, but this one vale seems very important. On my board and OCZ ram this gets set to the following on auto..
1600 - 4
1866 - 5

I have tried the following values with...

3 - Stable to 4.8GHz - Locks instantly at 4.9GHz
4 - Stable to 5.4GHz
5 - Stable to 4.8GHz - Locks instantly at 4.9GHz
6 - Stable to 5.4GHz

I'm sat wondering if its as crazy as odd values = bad and even values = good

Johny_dolan, your value shows as 5. Now it maybe very specific to the chip and RAM and motherboard come to that, but I wonder if a 4 in that value might make you stable?

Any guidence on this 'DRAM CKE Minimum Pulse Width' would be very welcome... I didi not really find much out on google.

Also some feedback... What value is yours set to and can you get a very high overclock?