Help me get Q9550 @ 4Ghz!!

You really need to read a guide on how to overclock that series of chip. The 1st bit of advice I can give you is that when motherboard features stop working, it usually means the PCI bus speed has been changed from the default of 100 Mhz. There is usually an option on most motherboards that allow overclocking to Lock the PCI Bus at 100 Mhz, if not, look for a manual setting, and keep it at 100Mhz. Worst case scenario is that it is synced with CPU bus speed. Then you will have to reduce the PCI bus speed in the same % that you are raising the CPU bus speed, so that the end result is the PCI bus speed is around 100Mhz.

Let me know if you have the option to lock the PCI bus at 100Mhz. Also check to make sure Spread Spectrum is turned off.

Re: lock the bus to 100Mhz- yes do that. Please also download CPU-z and check the bus speeds BEFORE you make the change, so you can see what its at, and what it goes to when you change it.

Re: Spread spectrum - usually located in the CPU overclock section, most modern motherboards default is Off anyways, so don't fret.

You gotta get teh info from CPU-z, while running the stable settings you've been running since your 1st post. That will let us see whats going on.

did you try 99Mhz?

also, are you sure your RAM isn't being overclocked too far?

Your RAM is being overclocked if its at 845 Mhz. Try dropping it to the next step below. Don't be concerned about performance from the RAM - read the articles at Toms and others that have tested memory in the modern age, and show that at most it has 1-2 fps difference, usually not even 1 fps. This may help out the overclock. Also, try the PCIe lock again once the RAM is adjusted slower.

There is also an option for FSB strap to Northbridge - try changing this from Auto to some of the other settings. It adjusts the Northbridge timings, and may let you boot past 422 mhz.

Well, not sure if you saw this page while searching, but I poached it from some forum. Just remember to monitor temps if it succeeds in booting.
(This is from a Asus P5QE)(Also, you could try getting 1066Mhz RAM to run at 848 or 896Mhz -just 1 stick to test with)

Settings for Q9550 for 3.6ghz - should be possible for every Q9550

Ai Overclock Tuner : Manual
CPU Ratio Setting : 8.5
FSB Frequency : 424
PCIE Frequency: 105
FSB Strap to North Bridge : Auto (p5q pro has some problems with straps)
DRAM Frequency: Auto, this will be set to 848Mhz (or change to the mhz of your memory)
DRAM Timing Control: Auto (adjust to your timings of your memory)

DRAM Static Read Control: Auto
Dram Read Training : Auto
MEM OC Charger : Auto
Ai Clock Twister : Auto
Ai Transaction Booster : Auto

CPU Voltage : Set what you need, this will range from 1.20-1.4v
CPU GTL Reference: Auto
CPU PLL Voltage : 1.50
FSB Termination Voltage: 1.30
DRAM Voltage : 2.1
NB Voltage : 1.2-1.5v (quads are alot harder than dual cores to clock, the NB voltage helps with the higher FSB on quad)
PCIE Sata Voltage: Auto

Load Line Calabration : Enabled
CPU Sread Spectrum : Disabled
PCIE Spread Spectrum : Disabled
CPU Clock Skew: Auto
MB Clock Skew: Auto



Settings for Q9550 for 3.8ghz - Might not be possbile on every motherboard (all motherboards overclock differently). CPU should be capable.

Ai Overclock Tuner : Manual
CPU Ratio Setting : 8.5
FSB Frequency : 448
PCIE Frequency: 105
FSB Strap to North Bridge : Auto (p5q pro has some problems with straps)
DRAM Frequency: Auto, this will be set to 896Mhz (or change to the mhz of your memory)
DRAM Timing Control: Auto (adjust to your timings of your memory)

DRAM Static Read Control: Auto
Dram Read Training : Auto
MEM OC Charger : Auto
Ai Clock Twister : Auto
Ai Transaction Booster : Auto

CPU Voltage : Set what you need, this will range from 1.20-1.4v
CPU GTL Reference: Auto
CPU PLL Voltage : 1.6
FSB Termination Voltage: 1.30-1.40 (try 1.3, and if its not stable, raise it)
DRAM Voltage : 2.1
NB Voltage : 1.2-1.5v (quads are alot harder than dual cores to clock, the NB voltage helps with the higher FSB on quad)
PCIE Sata Voltage: Auto

Load Line Calabration : Enabled
CPU Sread Spectrum : Disabled
PCIE Spread Spectrum : Disabled
CPU Clock Skew: Auto
MB Clock Skew: Auto

@IceVip 4ghz is a lofty goal bordering on impossible with your hardware and a Q9550, when you increase the FSB you're increasing the Kingston 800mhz memory speed, and Kingston was not very accommodating back in those days as allowing to be pushed too far past it's spec'd speed.

I overclocked my Q9550 to 4.0ghz so your title pulled me in, in hopes you had the hardware that could actually get you to 4ghz which IMO you do not have, and your 4ghz goal is just not going to happen for you.

However I would absolutely love for you to prove me wrong regarding this, it's just from my experience I know what's in store for you, and how hard it is to get a Q9550 to 4ghz.

Your motherboard specs listed it could run DDR2 1066mhz memory, which would have given you more of an edge, but still not enough to get you to 4ghz.

Those of us that reached 4ghz shopped at the time for the best of the best overclocking motherboards that could run DDR3 memory and I reached 4ghz running 2,000mhz memory, simply because the memory could handle jacking up the FSB, then fine tuning the PLL, VTT, and GTL voltages.

Have you even considered possibly upgrading to maybe a Sandy or Ivy bridge setup, because even a Sandy bridge 2500K not overclocked will deliver your gaming desires.

Could you afford a memory upgrade?

http://www.newegg.com/Product/Product.aspx?Item=N82E16820231246