Alienware Aurora R4 i7 4820K not factory overclocked from 3,7 to 4,2GHz?

download something like CPU-Z

it should report on the actual speed of each of the cores.

Only Core#1 is factory overclocked to 4.2GHZ.

I don't run Windows 8, so I can't tell the exact key strokes, however, you should be able to access the Bios on start up.   One of the settings will refer to overclock, voltage, or cpu settings.  It will not be the same group as the turbo boost setting.  Move over and select it.  You may need to look around a little in there to find it.   

Traditionally, Alienware puts a special key setting at the bottom of the CPU/volatge category that says "Load Level 1 Overclock".  Select it.  Back out 1 screen.  Save and exit.    This is not the same as "Load Optimal defaults" - that will put your chip back into it's original stock settings.  I would load CPU-Z anyway, just so you can learn how the chip behaves under certain conditions.

Your RAM frequency has a multiplier of 2.  So my DDR3-1600 MHz RAM is really 800MHz.  This is normal.  In your case, it's probably really 799.xx something X 2, so it is at its maximum.  Also be aware, that when you (or Alienware) overclocks the CPU and changes the Base clock, they have to make sure the memory multiplier (changeable to 6, 8 or 10) X base clock does not exceed your RAM max frequency, in this case 1600.  It is very common for your memory to run at sub-maximal speeds.  If I have a base clock of 160, I can use a memory multiplier of 10 to get my 1600 exactly.  But if I want to up the base clock speed to 175, I 'll need to reduce my memory multiplier to 8.  (175 X 10 = 1750 too much)(175 X 8 = 1400).  My memory is now underclocked, but it is necessary to increase the CPU speed.  I don't want to turn this into a post on overclocking and I have been deliberately casual in my explanation. However, I think a basic understanding is necessary.   After activating your factory OC, you may see your memory speed drop below it's current setting.  This is normal and necessary. and no... your CPU performance won't be slower.

Hi,

Thanks for the answers. Yes when I look into the bios I actually see 2 overclock levels... I have load level 1 or load level 2. I have tried both but I don't see any differences in settings. (when I go into the overclock menu everything is still set to 'auto' after I load aither overclock level, then save, then reboot, and go into bios again.

Don't worry about the Auto setings (in fact, make sure you don't change them at this point).  All of those relate to voltage levels.  Your CPU/MB will adjust the voltage levels to match what's needed.  The auto levels are meant to be safe, but people who get up on the high end of overclocking will try reduce their voltage to a thinner margin to keep temps down.  The only number that should change is your base clock (BCLK) and possibly the memory multiplier (6, 8, 10 etc) and you should not have to change anything except select 1 of those 2 OC levels.

OC 1 and OC  2 are the right settings.  Dell often sells the same chip at various CPU speed levels.  The Bios has been pre-loaded with both levels they sell (or did sell).  I don't know which is your 4.2 level, but my gut feeling is OC 2 is your 4.2 and OC 1 is a 4.0GHz level they may have sold in the past.  Here is where you need CPU-Z or another monitoring program to see what's happening.  Be aware, you also likely have Speedstep and C-State running within the Bios (you should).  These features will reduce your CPU speed when not needed, keeping temps and power usage down.  Right now as I'm typing, my CPU is sitting at 2136 MHz.  As soon as I actually do something that requires some effort (like launching a program), one or all of the cores will light up to 4211 MHz.

Besides CPU-Z, you can also try HWMonitor (same company as CPU-Z).  It's the default monitoring program for many users.  I have recently started using HWiNFO64 for the same purpose.  It has a nice little core meter that sits in the corner so you can watch your CPU go up and down and a simple summary that will let you now if Turbo, C-State, and all your other chip features are on or off.  It also records averages and CPU frequency maximums, so it useful for learning how your hardware works.

Get a monitoring program up, and load overclock level 1.  See what it frequency it tops out at.  Unfortunately, I don't have anything in this family of chips, so I can't give you exact numbers, but I do know your chip has a multiplier in the 39-42 range, which would make your base clock around 100. Those are the numbers to look for, but again, you should NOT be changing any values other than selecting the Overclock 1 or 2 settings. Also, it is highly likely enabling the OC 1 or 2 will disable the "Turbo" setting.  This is a good thing.  The Turbo only ramps up the frequency on 1 core, and only when the other cores are not heavily taxed.  To safely run it, you need to set voltages like all the cores would run at that higher level, when it fact, only 1 will.  Kind of the worst of both situations.