Overclocking q6600 instability over 3 ghz -SOLVED- try when having OC issues

[_Faust_]

Hi everyone, I need a little help on my overclocking.

I'm having major issues getting my CPU stable at clockspeeds higher than 3 GHz;I'd like to get some advice on what to do next.
I use Prime95 for testing stability (if Vista 32bit even starts )
I get like instant errors on starting a test (when doing the small FTT test, standard test lasts longer). Usually Core4 fails first.

First off, my specs:

Q6600 G0 @ 3,6 ghz (FSB 1600 mhz, x9)
Asus striker II NSE motherboard
OCZ 12800 1600 mhz RAM (2 gb x2)
3x 8800 Ultra SLI superclocked @ 675 mhz
Tagan 1300W PSU

everything is watercooled, GPU's, CPU, north & southbride, MOSFETS and my harddisk (All koolance stuff if someone wants to know)



Voltages:
I tried at first leaving everything at auto, with no success.
Then, I started raising voltages stepwise using a friends reference voltages as a start (same rig, stable 3.6 ghz overclock).

I went to the following max voltages, and there is where I gave up:
Vcore is @ 1.59375 V
VTT 1.44V
CPU PLL 1.62 V
NB 1.66 V
SB 1.6 V
memory 1.92 V

These are BTW the Bios settings, CPU-Z & everest read usually a little lower values.

I disabled Spread spectrum, speedstep, C1E, CPU thermal management. etc.



Core temps on the CPU are now getting very high (75 under load). Sometimes the whole system just freezes and I need to reboot (I even had freezes in the bios).

So my question is, what should I try next, or is this CPU just a bad overclocker and should I give up. Or is some other voltage causing the lockups?

Ow yeah, today I upgraded my bios from 0702 to 0805, maybe that helps.

BTW, I have no clue what the CPU PLL voltage is, who has an idea whats it for?

Any help would be greatly appreciated!

[_Faust_]

Allright, I have found a solution!
For some odd reason when I select a FSB of 400 mhz and a multiplier of 8 instead of 9 (3.2 ghz) it's stable at relatively low voltages. HOWEVER when I'd select FSB of 355 with a multiplier of 9 things are unstable as f*ck.
No matter how high you raise whatever voltage!
So for anyone else running into this sudden overclocking wall when overclocking: Try using a lower multiplier, especially in the 360-400 mhz FSB range. I also linked my RAM:FSB frequencies to sync (2:1).

edit: I'm currently stable @ 1.32V 3.2 ghz.
All other voltages at auto.

[Level 88]

It's those pesky straps, I tell you. I'm having problems on my P5Q with Q6600 that doesn't want to POST *AT ALL* (it's just dead, spinning wheels, dead hamster sorta thing) if I select FSB >= 400MHz on any strap, or set the strap to 400MHz at any FSB.

[_Faust_]

Thats weird, but is it a motherboard problem or a cpu problem? I mean, there are people with pretty much the same rig as me and they use a 9x multiplier with success. peculiar, really....

Second, I ran Prime95 yesterday for hours and it was very stable, no problems. HOWEVER when I started running games things froze after hmm 5-15 minutes of play.
So I upped the southbridge; no success. Upped Northbridge; no success. In the end I upped my Vcore a whole bunch and that helped. So how come that games can cause instability on the CPU while prime95 cant? Different kind of load?
I did both small and high FFT tests.

[_Faust_]

Ow yeah, I found a great thread on what the PLL voltage is. In a nutshell: Does something with the fsb frequencies in your CPU, dont mess with the values doesnt help you with anything but frying your CPU.
Read about it here:
http://www.xtremesystems.org/forums/...d.php?t=179757