Overclocking i7 950

[Pacwageo]

Hey folks,

I want to overclock a core i7 950. My goal is to get it around 3.8 GHz.

Here's my computer:

CPU:
Core i7 950
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115211

Mobo:
ASUS Sabertooth x58
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131665

CPU Cooler:
Scythe air cooler with Arctic Silver thermal paste
http://www.newegg.com/Product/Product.aspx?Item=N82E16835185142
http://www.newegg.com/Product/Product.aspx?Item=N82E16835100007

RAM:
G Skill DDR3 1600 (Tri channel)
http://www.newegg.com/Product/Product.aspx?Item=N82E16820231225

PSU:
OCZ 700W
http://www.newegg.com/Product/Product.aspx?Item=N82E16817341018&cm_re=OCZ_PSU-_-17-341-018-_-Product

The rest of the components aren't too important so I won't bother posting them....

I am trying to use the intel tuning utility but I'm not sure what to change the voltage to in comparison to the clock frequency.

Anyone have an idea of what I should set my settings to to achieve 3.8GHz?

Thanks

 

[Colonel_Panic]

You can probably do the math on that. With a multiplier of 20 you'll need a base clock of 190 MHz, 21 gives you 180 MHz. This is from what I've read, as I've yet to OC my 950. Hopefully this can be done with a voltage of say, 1.35V.

 

[Pacwageo]

So there's no exact science to what voltage you have to set it to? You have to guess and test it out?

 

[Colonel_Panic]

Exactly. Overclocking CPUs is as much art as it is science. Stability of your chip depends on so many different factors that isn't almost impossible for 2 overclocks to use the exact same settings. You might reach 3.8 GHz with 1.35V and someone else with a different mobo or cooling solution might reach 4.0GHz on 1.28V. It's a bit of a crapshoot. And considering that boosting the OC means tweaking some settings then testing until collapse, a lot of people aren't really that interested in it.

 

[djoye]

I'm at 4.2GHz (200×21) with 1.325V and my 4.0GHz OC (174×23) was at 1.255V I think; can't remember exactly. Your voltage requirements change depending on your BCLK.

I would find out how to get 3.8GHz and run your RAM at 1600MHz.

I would try these settings:
CPU multiplier: 19
BCLK: 200
DDR multiplier: x8
Uncore multiplier: x16
QPI multiplier: x36

I would start with these voltages:
CPU: 1.3V
QPI/Vtt: 1.35V

Also verify that the BIOS is configuring your RAM properly. That has held me back in the past when I didn't know any better. If it isn't already set, then set your RAM voltage to the specifications given for that RAM (looks like 1.5V); if your BIOS reads the RAM XMP (Profile) then enable that setting.

I guess you're running IntelBurnTest. Manually select 8 threads, let it do its 5 runs and if it passes then boot back to the BIOS and drop the CPU voltage a couple notches. I think you might be able to start around 1.275V and work down from there. If IntelBurnTest says you're not stable or if you get a BSOD with a 0x00000101 code or a random 0x000000A# code then bump up the CPU voltage a notch*** and try again.

Once your CPU voltage is stable then start dropping the QPI/Vtt voltage and testing until you get instability. 0x00000124 BSOD indicates not enough QPI/Vtt voltage and IntelBurnTest may even warn you if you don't crash.

***If you crash at X voltage then I recommend going up two notches in the BIOS from that voltage and trying again. If it then passes burn test I'd leave it at that.

 

[E4g1e]

Some people that have been successfully running at 200x21 or 200x19 are actually using the now-discontinued i7-920. The i7-950 has, on the other hand, a maximum turbo multiplier of 24x (23x non-turbo). This makes it a bit more difficult to achieve both a high CPU clock speed and a high memory speed at the same time. And due to a logic bug the Nehalem CPUs overclock better at odd multiplers than even ones. For the i7-950, disable Turbo mode (this will set the maximum multiplier to 23x unless you have one of those X58 motherboards that can hold the 24x multiplier with both Turbo and EIST turned off, in which case you will have to manually set the multiplier to 23x) - and to get to 4.0 GHz, a BCLK of 174MHz is needed. With the memory multiplier set at 2/8x, this would result in the memory running at an effective DDR3-1392 speed. All other voltage settings are starting points; just keep tweaking them until you've hit the best balance between stability and heat (power consumption).

Or, for 3.8GHz, set the BCLK to 166MHz (this would result in a clock speed of just over 3.8GHz, with the memory running at DDR3-1333 speed at a 2/8 ratio).

Of course, you can set a lower CPU multiplier. Just make sure that you raise the BCLK accordingly to compensate. However, running the IMC above DDR3-1333 speed may require a boost in the QPI/Uncore voltage.

 

[martinje]

You know my I7-950 likes the multi @ 20 over 21 for some reason. Tried many volt settings and I cant get it stable with a multi of 21 bus 200 with HT/Turbo on. It was requiring way to much voltage something like 1.395 on the CPU side more then my Coolit 240 could handle with being to close to the 100C on stress test.

Now I have multi at 20 with the bus @ 205. Im running at 4.1 ghz and mem is almost 1600 its like 1597 or something of that sorts with a voltage of 1.365 . I have both HT/Turbo on.

By stable I do the following

25 passes of Lynx / 1 hour test of OCCT random timings / 2 hours of Prim 95

For some reason my I7-950 likes that better. weird I know. ???