Preface to OC:
you start overclocking it is important to know what type of memory and cooling
you have, first you want to OC the CPU and then the memory separately as to not
cause issues which are harder to pinpoint. After you change each setting you
should use a stability test such as Prime95 or IBT to test for stability before
going up another notch.
Step #1 Overclocking the CPU
On Ivy Bridge overclocking is done through the CPU Multiplier on a “K”
series SKU like the 3770K and 3570K and the multiplier is multiplied by the base
clock. When you overclock the base clock you are overclocking the DMI and PCI-E
busses as well, so you might damage or corrupt the devices hooked up to these
busses such as your HDDs/SSDs and GPUs on the PCI-E bus.
CPU Frequency = CPU
Multiplier X Base Clock
Frequency = Memory Multiplier x Base Clock
That means if you increase base clock you increase
both memory and CPU frequencies, you also increase the iGPU’s frequency as well.
However with Ivy Bridge you shouldn’t be increasing the Base Clock for Air/H2O
overclocking as BCLK OC takes a toll on everything on the PCI-E bus including
your GPUs and your SSD/HDDs, so it is pretty much reserved for benching with
colder temperatures. Don’t worry about increasing BCLK for memory speeds as
there are enough memory multipliers with Ivy bridge/Z77 so you can always find
the speed you want unlike with Sandy Bridge. However you can increase the BCLK
slightly for high memory OCes where certain multipliers are better than others.
What I shoot for is a stable
4.6-5GHz OC with Ivy Bridge, such as something like this:
are much better than that of the 5GHz shown earlier, topping out around 90C
under full load, also the wPrime score, while the benchmark and OC aren’t
tweaked, shows it being faster at this speed as the temperatures are lower and
the CPU isn’t throttling.
With Ivy Bridge, you want to slowly increase the VCore
as temperatures will hurt your max OC much more than voltage can stabilize it. I
would go one multiplier at a time sticking to my voltage ranges in the graph
below. If you end up with too much heat then the logical thing would be to
decrease the voltage, however at this point you can try to decrease the CPU PLL,
and if that doesn’t help much you can always decrease the VTT and System Agent
(IMC) to levels where they are lower but still remain stable. When I was messing
around with LN2 I could validate 5 GHz with less volts than my CPU needed at
stock frequency, that is how much heat has an impact on frequency. However I do
not want to show that shot as people might not always read stuff, but 5 GHz at
1.2v isn’t impossible at -190C.
Below is a chart
that shows the optimal voltage settings which you should aim to better:
You should try to fall
under these voltage ranges or slightly above to stabilize your OC, these are the
recommended voltages per frequency, however the CPU I used is very good it seems,
so you might need more voltage than I did.
Above you can see where it says CPU/PCIe Base Clock as well
as the CPU Clock Ratio which is the CPU Multiplier and the System Memory
Multiplier. With just increasing the multiplier you can increase the clock
speeds of the CPU up to about 4.2 GHz with 42x100.00. If you want a set 100 MHz
even base clock it is best to set the base clock to 100.00. SVID will stabilize
the CPU to about 4.2 GHz but not beyond that, so you will need voltage increase
above 4.2 GHz.
If you want the best results you should
disable power saving options like I have below, however if you want the CPU
frequency to drop under idle conditions, you should leave them enabled. You
should also leave them enabled if you will use DVID Voltage offset instead of
fixed voltage. If you decide to leave on power saving options, make sure that
you increase the turbo current limits for the CPU within the turbo settings list
to 200A and 300W to totally maximize Intel Turbo limits; however this might not
Any overclocks above 42x
will probably require VCore increase, and this can be done through the CPU
You will also want to set LLC which
is under the 3D power menu, the LLC should be set to Turbo for a slight droop,
or Extreme for no droop at all. The LLC on these boards is rock solid, what you
set is what you get, and nothing other than that. If you want you can also mess
with the other PWM settings, but that shouldn’t be needed as Ivy Bridge doesn’t
pull enough power to warrant those changes under air cooling. I recommend a
slight drop of voltage under load, this might help with temperatures.
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