1) Hum looks like a temp issue - Check Core Temp in Bios (Hardware monitoring) 2) What is your memory frequency,timings and VDimm in Bios (stock 1600MHZ or overclocked) - do you get a post boot code message from the P55 FTW? Also try Vcore=1.3V and VTT=1.225 (Boot) and 1.275 (Eventual) (instead of 1.4V)

Got a new chip today. Doing some LinX testing only 5 passes to play around and see how it does. Just having fun with it tonight, will go back later and test for true stability.

My overclock has gone well, but still runs way too hot.  I need help in turning down the correct voltages to get the temperature down.  I started with the exact settings from post #1 and it was stable at 4.20GHz and 1.300V but the CPU ran way too hot for prime95-blend (over 90C in just a minute or so).  First I dropped the multiplier to 20x and then started dropping CPU Vcore in steps down to 1.2125V.  It ran overnight (11 hours) without fail but the cores were between 80C and 90C.  Still too hot.  (1.2000V was not stable.) One more thing, in the CPU Configuration menu, I disabled SpeedStep because it was going to 22x and causing things to get even hotter.  (Hmmm that's odd.  I just went to check the SpeedStep setting and it is grayed out and won't let me enable it.  ???)

So -  do I just keep dialing down the multiplier and CPU voltage -OR-
 is there some other setting (like CPU VTT) that I should also be reducing to get the heat down?
(What is the desired relationship between CPU Vcore and CPU VTT?

EVGA P55 FTW / i7-860 (Rev. B1 / SLBJJ) / G. Skill 2GBx2 DDR3-2000 9-9-9-27  (FSB 200Mhz; 2:10)
Corsair TX850W / noctua NH-U12P with Arctic Silver 5  dual fans blowing horizontally towards back /
Antec Nine Hundred; all case fans on Meduim except top fan is on High
 (top HD cage moved up 2 slots to blow directly on CPU; 2x HDs in very bottom.)

- Dan

I'm thinking of buying an EVGA P55 SLI motherboard, an Intel Core i7 860 CPU and 8 GB of DDR3-1600 memory. My idea behind choosing the EVGA P55 SLI motherboard is to overclock my CPU at around 4 GHz on air cooling.
 
So, the following guideline is exactly what I need to fulfil a good overclock of my future Intel Core i7 860 CPU:
 

EVGA_JacobF
So today our goal is as follows:

* Using an Intel Core i7 860, overclock to at least 4.2GHz on air.
* Run DDR3 memory in Dual Channel at 1600MHz, 9-9-9-24.
* Run a BClock frequency of 200MHz or higher.


1. So the first thing we want to do is go into the BIOS, and press "Load Defaults", save and exit and go back into the BIOS and navigate to "Frequency/Voltage Control"
2. Next we will adjust the following options:

* CPU Multiplier Setting to 21x
* CPU Frequency Setting (AKA BClock) to 200MHz
     This will give me exactly 4.2GHz (21x200)
* PCIE Frequency Setting to 104MHz. (In some cases this can help maximize BClock)
* QPI Frequency Selection to 4.270 GT/s
* EVGA VDroop Control - Without VDroop
* Bootup CPU VCore - 1.30000V (good for starting point, will likely need to increase for 24/7 stability)
* Eventual CPU VCore - 1.30000V (good for starting point, will likely need to increase for 24/7 stability.)
* DIMM Voltage - 1.65V
* Bootup CPU VTT - 1.400V
* Eventual CPU VTT - 1.400V
 
3. Next we will go under "Memory Configure" and adjust my memory to it's specifications. In my case, I am running 1600MHz memory so I will make the following adjustments:

* Memory Frequency to 1067MHz (AKA 2:8).
* Memory timings adjusted properly per memory specifications.
* This will give me 1600MHz memory. (200x8)
 
4. Finally, on the "CPU Configuration" page, we will make the following critical change:

* Intel C-STATA Tech - Disabled

 
However, the third step is a bit beyond my grasp. If you're running DDR3-1600 memory, why do you need to adjust the frequency to 1067 MHz, from where does the 2:8 ratio comes from and how later, you again get your memory to run at 1600 MHz?
 
Also, what's the differences between Bootup CPU VCore, Eventual CPU VCore, Bootup CPU VTT and Eventual CPU VTT?

I know the memory clock and CPU clock are the same but I don't understand why was the memory frequency adjusted to 1067 MHz to finally run at 1600 MHz.
 
Also, what about Turbo Boost function; should it enabled or disabled?
 
Another thing is that I want to know the differences between Bootup CPU VCore, Eventual CPU VCore, Bootup CPU VTT and Eventual CPU VTT?

I've think I've got it about the memory frequency stuff. However, the VCore and VTT things are still tormenting my mind...

That's what I guessed but I needed to be sure... Thanks!

However, what's the difference between VCore and VTT?

I've been searching at other places and all I could understand is that CPU VTT is the CPU termination voltage. Is it true or not, I don't know and I would appreciate it if someone could confirm this and elaborate a bit on it.

What about the Turbo Boost function; have you enabled it or disabled it? Also, what VCore have you mentioned above; Bootup VCore or Eventual VCore?
 
Finally, is there nobody who can help me in differentiating between VCore and VTT?

Varun

What about the Turbo Boost function; have you enabled it or disabled it? Also, what VCore have you mentioned above; Bootup VCore or Eventual VCore?
 
Finally, is there nobody who can help me in differentiating between VCore and VTT?

VCore's effect is on the overall CPU frequency , eg, 4.2GHz, 4.0GHz
VTT's effect is on the host frequency and ram frequency , eg, 133mhz, 200mhz, 1333mhz ram, 2000mhz ram

yahhhh

Be careful with this guide.  It seems to be assuming what was safe for Bloomfield is safe for Lynnfield, and Intel says that isn't the case.  For example it says 1.4V VTT, but Intel says anything over 1.21 will result in permanent, irreversible damage that will make your system increasingly unreliable until it outright fails.  Sure, overclocking itself is outside specifications, but Intel says Vcore can go up to 1.55 in the same table so it doesn't seem they're being TOO conservative on what is safe or not for 1156 socket CPUs. 

You can read more about it here: Link

Basic gist is Intel says above 1.15V and below 1.21V you decrease the lifespan of your CPU but if you return it back to 1.15V you should be ok.  If you go above 1.21V VTT it can cause permanent damage that even when reverting to stock settings will persist.  (these are for Lynnfield -- Bloomfield (1366) can take higher voltage)

The same spec sheet says the absolute maximum VCore you should run is 1.55V.  That tells me it isn't just a case of Intel being too conservative.  Running VTT at 1.4V is almost like running your VCore at 1.7V if you look at what Intel says the absolute maximum the chip can take before damage occurs.

Yes that's very disconcerting. I've also been reading that there may be benefits to increasing PCH voltage, but am disappointed to see that it isn't mentioned in this guide. I'd be interested to hear some recommended values for PCH voltage when overclocking.

I have been running at 1.4vtt for about a month and a half now, no problems, all is well.