Overclocking a I7 920 C0 to 4gz...

Dave2150 · 14 Sep 2009 at 03:36

I've had my I7 setup for almost a year, running at 3.4Ghz with no issues on a Asus P6T Deluxe (the original one, not v2).

I decided to try and squeze more power out of it and try for 3.6Ghz or even 3.8Ghz but my system refuses to boot when I increase the FSB past 170.

Here are the settings im running:

Multi: 20x
BCLK: 170
DRAM: 1534 Mhz
Uncore: 3047 Mhz
QPI: 6857 Mhz

CPU 1.35
PLL 1.88
QPI 1.35

I updated the P6T to the latest bios but i have the same issue, no POST after I increase the BLCK to 175.

Im using DDR3 PC3-10666C9 1333MHz memory.

I notice there is now a "V2" version of my board - was it replaced due to overclocking issues?

Im tempted to buy a 920 DO stepping but I'm not too sure my board could even take it to 4Ghz.

Cooling is a Noctua NH-U12P SE1366, idle speed is 45, load 80dc.

PSU is an Enermax Galaxy 1KW.

Any help welcome.

Tweaker · 14 Sep 2009 at 04:19

Im in the middle of finding a stable OC at the moment, with HT turned off, i have

Multi: 20x
BCLK: 191
DRAM: 1528 Mhz
Uncore: 3438 Mhz
QPI: 6876 Mhz

CPU : 1.35
QPI : 1.33

Its stable in P95, just need to find out how to get it stable with HT, though i think i could put turbo on and hit 4011mhz. Will let you know it goes, though i think its either or on the C0, unless you have water cooling. On air, it seems like 3.8 is the top.

game4it · 14 Sep 2009 at 10:03

Hi dave,
I'm using same cpu with a p6t and my mobo does not like 20x at all so i use 21x instead.
191x21 is what i use for 4ghz but i need 1.415v for it to be stable.

I would suggest to you that you run your ram slower than its rated and keep the timings loose also until you get the cpu at the OC you want.Then work on bringing the ram up to speed.

What sort of case and cpu heatsink/fans are you using as the c0's get very hot around 4ghz.
Can you post up the bios settings so we can have a look.

Dave2150 · 14 Sep 2009 at 13:36

game4it said:
Hi dave,
I'm using same cpu with a p6t and my mobo does not like 20x at all so i use 21x instead.
191x21 is what i use for 4ghz but i need 1.415v for it to be stable.

I would suggest to you that you run your ram slower than its rated and keep the timings loose also until you get the cpu at the OC you want.Then work on bringing the ram up to speed.

What sort of case and cpu heatsink/fans are you using as the c0's get very hot around 4ghz.
Can you post up the bios settings so we can have a look.

Thanks a lot for this help - I read a few guides which said to use the 20x multi so I hadn't even tried the x21.

Im now running "stable" at 170x20, 3.55Ghz. Again, increasing the FSB TO 175 results in no post.

Temps when running Prime85 on all 8 cores are 88-90dc, this was after running small fft's for 1 hour.

Bios settings are as follows:

CPU RATIO 21.0
BCLK 170
PCIE 100
DRAM DDR3 1100 (low for finding max bclk)
CPU Voltage 1.25v (stable at 3.55Ghz)
CPU PLL 1.88
QPI 1.35
IOHH 1.1
IOH PCIE 1.5
ICH VOLTAGE 1.2
ICH PCIE 1.5
DRAM V 1.64

CPU virtualization is turned off, speed step turned off, CPU clk screw off.

game4it · 14 Sep 2009 at 14:33

I leave these on auto as they dont seem to help me at all.
CPU PLL
IOH
IOH PCIE
ICH VOLTAGE
ICH PCIE

That a nice low vcore for 3.55ghz compared to me BUT those temps are way to high imo.You will not be able to reach 4ghz with the temps as they are because the c0 temps rise a lot when you get closer to 4ghz.

Next thing to do is try reseating the heatsink.
How much and how did you apply the thermal paste?
What case have you got and how many fans?

Dave2150 · 14 Sep 2009 at 15:02

The Noctua heatsink has a very thin layer of as5 and has already been reseated previously, case is a CM stacker with 2x120mm fans as the intake, 2x120mm fans as the outtake and the 200mm? large fan on the 1kw enermax psu.

My system temp is 45dc at idle - this seems very high considering the room temperature.

Ambient room temperature is 23dc.

Im aware that at 4Ghz temps would be way too high but I cant even post at 175 BLCK, thats obviously at idle where temperature wouldnt affect it, so this leads me to believe I have a very poor clocking motherboard?

I am going to "upgrade" to the Corsair H50 watercooler when I find somewhere with stock, hopefully this will bring temperatures under control.