CPU-NB: Experiences with overclocking the Northbridge?

[OnGsTa]

What's everyone experience with overclocking the CPU-NB?

From what I can gather, the highest possible is what we should be aiming for correct?

This articile from Annandtech seems to say so:
http://www.anandtech.com/show/3877/a...ance-scaling/7

However, this person's testings have shown that it's relative to what speed you're running your CPU at?
http://www.overclockers.com/the-impo...the-phenom-ii/

Anyhow, I managed to get the following settings fairly stable at the moment:


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965BE/Asus M4N98TD Evo (massive vdrop/vdroop with this board)
200x20 = 4000Mhz (1.6v bios/1.5v load) 53c max under prime95 load
CPU-NB = 2600Mhz (1.25v)
Ram = 1600/9-9-9-24-1T/1.5v

All other voltages have been left stock, C1E and C'n'Q have been turned off.

Was just wondering what's everyones thoughts on trying to push for CPU-NB of 2800-3000Mhz or not?

Thanks,
Andy

[m0n4g3]

Most benefits are obtained between 2600-2800. Anything higher than that take a BUTTHURT of voltage to get, and generally are kept for extreme cooling (dice/ln2).

You will notice a fair bit of difference performance wise going from 2000-2600/2800 but not between 2600-2800.

Also, i don't know how many times i recommend it... but PhenomMSRTweaker to lower your idle temps specially when pushing 1.4-1.5v...

Create custom cool and quiet profiles that work for you. I had my 1090t running the below profiles:
P0 4.0ghz @ 1.35v
P1 3.2ghz @ 1.25v
p2 2.4ghz @ 1.1v
P3 1.6ghz @ 1.025v
P4 0.8ghz @ .85v

My idle temps were insane! (1c above ambient) and this affected my short term load temps of +8c above ambient, which then shifted to +12c above ambient after approx 30 mins.

Also good savings on power usage, and easy as hell to setup!

[Jon187]

Originally Posted by m0n4g3

PhenomMSRTweaker

Good to know.

[m0n4g3]

Originally Posted by Jon187

Good to know.

Good to also know that you can lock in particular P-states to test the stability of them in the advanced settings.

Set the lowest and highest Pstates to the same and then prime that p-state.

Good to find the LOWEST achievable voltage on a set speed.

[OnGsTa]

Looks like anything above 2600Mhz for the CPU-NB was too unstable, ended up settling for 3.8Ghz/2600Mhz at 1.4875v/1.4v bios/load respectively.

m0n4g3 - I couldn't figure out how to get it to work properly? I set up P0-P4, went into service and click "activate Cool N Quiet" (bios version is turned off) and hit apply but it didn't auto-underclock?

[m0n4g3]

Originally Posted by OnGsTa

Looks like anything above 2600Mhz for the CPU-NB was too unstable, ended up settling for 3.8Ghz/2600Mhz at 1.4875v/1.4v bios/load respectively.

m0n4g3 - I couldn't figure out how to get it to work properly? I set up P0-P4, went into service and click "activate Cool N Quiet" (bios version is turned off) and hit apply but it didn't auto-underclock?

It's been a while since i've used it now, but there should be 2 ticks you need to enable. The service and the custom cool&quiet. Then also in the windows power settings ensure balanced is used.



So in the above screen ensure that you tick enable C&Q, and also Make P-States permanent.

Then once that's done, setup your p-states in the main windows then go back to it and click on Use Current Settings.

This should make them permanent. Also, play around with the #'s in the last 2 options there. They determine how many samples at the cpu usage will determine when P0 kicks in and when the rest kick in.

I used to set it to 5 and 9 before (fairly conservative on o/c's).

Also for 2600 you shouldn't need 1.4v, try bringing it back a touch... i used to be able to get 1.3 for 2600.

[OnGsTa]

Thanks, I'll try that tonight!

Sorry my last post was a bit unclear.

3.8Ghz at 1.4875 bios vcore/1.4 vcore under load

2600Mhz is at 1.25 CPU-NB voltage.

[m0n4g3]

How did you go Ongsta?

Did you get it working mate?

[OnGsTa]

Originally Posted by m0n4g3

How did you go Ongsta?

Did you get it working mate?

Indeed!

It crashed a few times, but then logic clicked in and I realised that for the P1, P2, P3, P4 states had CPU-NB at 1.1v instead of 1.25v. I figured the CPU-NB was still 2600Mhz regardless of which P-state/clock speed was running, so it needed a constant 1.25v.

Did a quick few minutes of prime at each state and they seem fairly stable.
I'll take me a week to make sure each state is prime stable though, a day for each state left priming over night.

The only limitation I've seen so far, is a max 1.55v setting. Because I require 1.6v in BIOS, which drops to 1.5v underload, I can't run my CPU at 4GHz.

Having said that, an extra 0.15v for 200Mhz to hit the 4Ghz mark is really just e-peen stroking.

[OnGsTa]

Oh and just FYI, my settings are:

P0 - 3.8Ghz: 1.5v/1.25v (CPU/NB) - load brings vcore down to ~1.4v
P1 - 3.4Ghz: 1.4v/1.25v (CPU/NB) - load brings vcore down to ~1.3v
P2 - 2.4Ghz: 1.2v/1.25v (CPU/NB) - load brings vcore down to ~1.1v
P3 - 1.6Ghz: 1.1v/1.25v (CPU/NB) - didn't check load
P4 - 0.8Ghz: 0.8v/1.1v (CPU/NB) - didn't check load

[rainwulf]

I have my NB running quite stable at 3000mhz, with the ram at 1600, and main cpu clock at 4000mhz.

1100T watercooled.

However, i cant get the damn thing a single notch above 4 gig.
The machine boots, but as soon as i power up OCCT, it instantly reboots within a second.
Would that high NB be causing that?

I am not sure being stable at 4.2gig with a lower NB make up for 3gig NB at 4gig clock.

[OnGsTa]

How much lower do you need to decrease the CPU-NB to get 4.2?

I doubt there's much difference between 4-4.2 on the CPU, but I've read in a few places that 2600 to 3000Mhz CPU-NB is a fairly decent jump.

Why don't you try both and monitor some framerates playing your usual games?

[OnGsTa]

Found it:
http://www.anandtech.com/show/3877/a...ance-scaling/7

[m0n4g3]

Originally Posted by OnGsTa

Indeed!

It crashed a few times, but then logic clicked in and I realised that for the P1, P2, P3, P4 states had CPU-NB at 1.1v instead of 1.25v. I figured the CPU-NB was still 2600Mhz regardless of which P-state/clock speed was running, so it needed a constant 1.25v.

Did a quick few minutes of prime at each state and they seem fairly stable.
I'll take me a week to make sure each state is prime stable though, a day for each state left priming over night.

The only limitation I've seen so far, is a max 1.55v setting. Because I require 1.6v in BIOS, which drops to 1.5v underload, I can't run my CPU at 4GHz.

Having said that, an extra 0.15v for 200Mhz to hit the 4Ghz mark is really just e-peen stroking.

Excellent! Nice to know it's still useful.

I run into both problems infact! I forgot to set the cpu-nb v's as well as my motherboard used to vdroop alot too!

1.5v would net me approx 1.45~ although i only needed 1.39 for 4.0ghz for me.

[Linkin]

Have my CPU-NB at 2.8Ghz/1.3v, does the job quite well.