e6750 on the road to 3.6

[Shujaa]

E6750 on an Asus P5K-E motherboard.

Air cooling but plenty of it (Ultra 120 + 120mm fan + healthy case airflow)
This is my first overclock so I'm having a little trouble getting it to stay stable at a higher FSB.

Currently my highest stable is at 3.4 using a 430 FSB and 1.40 Vcore (cpu multiplier is locked) and it works fine. I know the voltage is high but that's because I want to get it stable as high as I can first then look at cutting it back down.

At 450 FSB and 1.43 Vcore I booted into windows but had reboots / bluescreen within minutes of Orthos. Ran a Memtest and had no errors, so RAM is ok at this clock (1:1).

My question is what do I raise next? More Vcore? Or is something else holding me back - Northbridge, FSB... there are quite a few other voltages that can be adjusted in the BIOS but I don't know which I should tinker with, or what their safe limits are. Being new to this I'm a bit worried about going over safe limits for something and frying my mobo. Help appreciated.

 

[Dadofamunky]

Raise it to 1.5125. Vdroop will automatically drive it down to 1.41-1.42 under load and you should have no problems whatsoever at 3.6. The 6750s seem to have a wall beyond that, but 3.6 is totally doable with slightly higher voltages. Your cooler is excellent. My system is stable for 15hr. under Orthos and I never run my system as hard as Orthos does. I can send more specs if you want. Your BIOS is likely very similar to mine (my board is extremely new, and a microATX, but it seriously kicks butt).

I did so and it idles at 20C with a low-profile CNPS8700, which is the biggest cooler I can use in my system. Um, I also raised my Northbridge voltage a bit. My sig has more details. Is your RAM fast enough?

 

[Shujaa]

1.43 was my vcore after vdroop

It was actually set to around 1.53 in the BIOS, and both the BIOS and CPU-Z were reporting vcore as 1.43.

My RAM is fast enough, using 2x OCZ DDR2 800 Platinum sticks at 5/5/5/15 (they're rated for 4/4/4/12 at 800). I doublechecked with Memtest and had no errors with the memory. Maybe looser timings to be safe?

How do I know what to raise my NB to? BIOS doesn't report it, and it's set to Auto right now. There's only a few settings for it but I don't know which one is a small increase from its current voltage.

Also my temps under load were below 60 degrees (for the few minutes before it crashed), this cooler is indeed awesome Thanks for the help.

 

[soccerballtux]

Originally posted by: Dadofamunky
Raise it to 1.5125. Vdroop will automatically drive it down to 1.41-1.42 under load and you should have no problems whatsoever at 3.6. The 6750s seem to have a wall beyond that, but 3.6 is totally doable with slightly higher voltages. Your cooler is excellent. My system is stable for 15hr. under Orthos and I never run my system as hard as Orthos does. I can send more specs if you want. Your BIOS is likely very similar to mine (my board is extremely new, and a microATX, but it seriously kicks butt).

I did so and it idles at 20C with a low-profile CNPS8700, which is the biggest cooler I can use in my system. Um, I also raised my Northbridge voltage a bit. My sig has more details. Is your RAM fast enough?

I think something is wrong if you're getting 20C at idle. That's less than room temperature.

 

[Phunk0ne]

that is unusually high to have your E6750 @ 3.4GHz and already needing VID of 1.53 in BIOS.
In most cases, the P35 chipset needs a northbridge boost of +.01V in BIOS in order to stay stable. So if you haven't done that yet, than after you have added some volts to your Northbridge (MCH) you might be able to lower the voltage to your CPU # 3.6GHz
As soon as I wanted to hit speeds above 3.2GHz, I had to add some volts to the northbridge

Maybe you are just extremely lucky to have bought an E6750 that does not overclock well @ lower volts :-

here is are some overclock results I got with my P35 motherboard:

Result 1:

Undervolted
@ 3.2GHz
BIOS: 1.25V

Everest:
Idle @ 1.200V
Load @1.184 (ORTHOS)

FSB:RAM Ration @ 1:1
RAM Frew @ 400MHz DDRII-800
RAM @ 1.9V @ 4-4-4-12
Stock all over the board.

ORTHOS Stable
3DMark 06 Score: 13209

Temps:
Idle @ ~23C
Load @ ~37C

Result 2:

@ 3.6GHz
BIOS: 1.40000V

Everest:
Idle @ 1.360
Load @ 1.328 (ORTHOS)

FSB:RAM Ration @ 1:1
RAM Freq @ 450MHz DDRII-900
RAM @ 1.9V @ 5-5-5-15
MCH @ +.1V

ORTHOS Stable
3DMark 06 Score: 13729

Temps:
Idle @ ~25C
Load @ ~46C

Result 3:

@ 3.8GHz
BIOS: 1.50625V


Everest:
Idle @ 1.456V
Load @ 1.424V (ORTHOS)

FSB:RAM Ration @ 1:1
RAM Freq @ 475MHz DDRII-950
RAM @ 1.9V @ 5-5-5-15
MCH @ +.1V

ORTHOS Stable
3DMark 06 Score: 14086

Temps:
Idle @ ~27C
Load @ ~55C

 

[Shujaa]

I may be able to lower the vcore, it's simply that I haven't tried it - I set a generous amount just so I'd know it wasn't vcore holding back the system. As I said my temps are still at the comfortable range, so once I get a stable setting at 3.6 I will tone down vcore step by step until I find the optimum.

 

[Shujaa]

I just checked my Northbridge voltage settings, it's currently Auto but I only have the option to set it at one of the following voltages:

1.25
1.40
1.55
1.70

I guess I should just put it at 1.4 and see if it works?
Think I'll get some sleep and try some more after

 

[Dadofamunky]

Originally posted by: soccerballtux

Originally posted by: Dadofamunky
Raise it to 1.5125. Vdroop will automatically drive it down to 1.41-1.42 under load and you should have no problems whatsoever at 3.6. The 6750s seem to have a wall beyond that, but 3.6 is totally doable with slightly higher voltages. Your cooler is excellent. My system is stable for 15hr. under Orthos and I never run my system as hard as Orthos does. I can send more specs if you want. Your BIOS is likely very similar to mine (my board is extremely new, and a microATX, but it seriously kicks butt).

I did so and it idles at 20C with a low-profile CNPS8700, which is the biggest cooler I can use in my system. Um, I also raised my Northbridge voltage a bit. My sig has more details. Is your RAM fast enough?

I think something is wrong if you're getting 20C at idle. That's less than room temperature.

Call me crazy... actually it's averaging 23-24 now. Nevertheless it's running like a tank.

 

[Dadofamunky]

Originally posted by: Shujaa
I just checked my Northbridge voltage settings, it's currently Auto but I only have the option to set it at one of the following voltages:

1.25
1.40
1.55
1.70

I guess I should just put it at 1.4 and see if it works?
Think I'll get some sleep and try some more after

That should be fine...

Originally posted by: Shujaa
1.43 was my vcore after vdroop

It was actually set to around 1.53 in the BIOS, and both the BIOS and CPU-Z were reporting vcore as 1.43.

My RAM is fast enough, using 2x OCZ DDR2 800 Platinum sticks at 5/5/5/15 (they're rated for 4/4/4/12 at 800). I doublechecked with Memtest and had no errors with the memory. Maybe looser timings to be safe?

How do I know what to raise my NB to? BIOS doesn't report it, and it's set to Auto right now. There's only a few settings for it but I don't know which one is a small increase from its current voltage.

Also my temps under load were below 60 degrees (for the few minutes before it crashed), this cooler is indeed awesome Thanks for the help.

Don't raise it any further. That should be enough. Once you combine that with judicious northbridge increase, you should be rock stable. Your temps shouldn't be too much higher. If not, something else is going on. (of course, that's the last refuge of someone who doesn't know what he's talking about )

Also combine SpeedFan with CPU-Z and see if you get consistent readings. this means (a) your numbers are accurate or (b) both readings are equally wrong, which I guess is progress .

Looser timings might not help here; DDR2-800 memory has so many makers that it's unpredictable regarding how good the RAM is for overclocking.

 

[Regalk]

One of your OC limitations is the OCZ. I use the OCZ XTC rev 2 on the DS3L and it is a dog (compared to my Corsair, Mushkin, Crucial, Patriot and Crucial). In the end I stopped trying to run the OCZ at speeds in excess of 900 and ran close to 800 speeds. Maybe you should bump the voltage of the OCZ to 2.1 or 2.2 even though I doubt it would do any better
I use the P5K-E Wifi, Mushkin HP and E6750 and run at 467 X 8 fairly easily at 1.5V (the Asus has a huge vdroop issue).
I did increase the NB one notch.

 

[Shujaa]

Ok I raised my NB voltage step by step to its highest setting, didn't seem to make a difference. I get <30 minutes stability in windows.

If it is the RAM that's limiting me, wouldn't that show up errors in Memtest? It seems to be fine. How do I know for sure it's the RAM?

 

[MyLeftNut]

That's some high vdroop you got with that board. Perhaps a pencil mod would help. About the memory, usually if it's the ram that's unstable, orthos/prime should show rounding errors instead of restarting. Restarting is a sign of insufficient vcore/cpu instability.

 

[Shujaa]

I've tried almost everything, kinda disappointed. Upped voltages of NB and FSB too without luck. Of course I'll happily settle for my stable ~3.5 as there won't be any practical difference when I use it, just trying to figure out why

I did notice a couple options I'm not sure about in my JumperFree BIOS page:
Transaction Booster (Enabled, Disabled, Auto, and has a number setting from 0-3 when enabled or disabled)
Clock Over-Charging Mode (Auto, 0.7v, 0.8v, 0.9v, 1.0v)

Anyone know what these do? Playing with the Transaction Booster didn't seem to make any difference, but I didn't touch the other setting. Motherboard's manual has no explanation either.