Being able to run P95 for hours and hours does not mean that your overclock is 100% stable, I've had systems run P95 for 24 hours but still crash when playing games etc... If you can use all the programs that you use on a regular basis without issue then your overclock is stable, if not then you have to tweak further.
As for your memory set 'Ai Overclock Tuner' to 'XMP' mode and this will set your memory voltage/frequency/timings to the correct settings automatically and your ram will run @ 1600mhz.
Also your CPU frequency lowering to 1600 when not under load is normal, this is Intel's speedstep technology working as it should. If you change your CPU vcore mode to 'Offset' mode it will also lower your CPU vcore when not under load, saving you power and increasing the life span of your CPU.

For more info on overclocking using offset mode please see the link below.

http://rog.asus.com/forum/showthread.php?2162-Overclocking-Using-Offset-Mode-for-CPU-Core-Voltage&co...

Going to guess your BSOD was 101? Wild guess your need to add more V core. Why not try it at 1.3V

Anicra wrote:
Going to guess your BSOD was 101? Wild guess your need to add more V core. Why not try it at 1.3V

what is BSOD? is the blue screen after the system crash? the it says the system has to stop to prevent damage etc. and give me 100dumping stuffs w/e that is? thats what happen to me every time the system cashes.

BSOD = Ya, Blue screen of death. the long first number when you get a crash.
example
***Stop: 00000000000x101 (blah blah)
Also you could try, you could run Prime 95 ( blend on torture test) , or use Occt (AVX enabled for 2nd G Icore7) or LinX to test the stability over night.

I like using intelburn or LinX. Ill run Prime95 after I have passed on the other (when I have a long time I am not using that computer)

The OverClockers BSOD code list

BSOD codes for overclocking
0x101 = increase vcore
0x124 = increase/decrease QPI/VTT first, if not increase/decrease vcore...have to test to see which one it is
on i7 45nm, usually means too little VTT/QPI for the speed of Uncore
on i7 32nm SB, usually means too little vCore
0x0A = unstable RAM/IMC, increase QPI first, if that doesn't work increase vcore
0x1A = Memory management error. It usually means a bad stick of Ram. Test with Memtest or whatever you prefer. Try raising your Ram voltage
0x1E = increase vcore
0x3B = increase vcore
0x3D = increase vcore
0xD1 = QPI/VTT, increase/decrease as necessary, can also be unstable Ram, raise Ram voltage
0x9C = QPI/VTT most likely, but increasing vcore has helped in some instances
0x50 = RAM timings/Frequency or uncore multi unstable, increase RAM voltage or adjust QPI/VTT, or lower uncore if you're higher than 2x
0x109 = Not enough or too Much memory voltage
0x116 = Low IOH (NB) voltage, GPU issue (most common when running multi-GPU/overclocking GPU)
0x7E = Corrupted OS file, possibly from overclocking. Run sfc /scannow and chkdsk /r

BSOD Codes for SandyBridge
0x124 = add/remove vcore or QPI/VTT voltage (usually Vcore, once it was QPI/VTT)
0x101 = add more vcore
0x50 = RAM timings/Frequency add DDR3 voltage or add QPI/VTT
0x1E = add more vcore
0x3B = add more vcore
0xD1 = add QPI/VTT voltage
0x9C = QPI/VTT most likely, but increasing vcore has helped in some instances”
0X109 = add DDR3 voltage
0x0A = add QPI/VTT voltage

Not sure about the comment, more likely on those systems of the 0x124. I have been getting 0x101 when I have been overclocking the sandybridge E (seem that the Memory controller is more robust and less fussy). You know when you are tuning it down to get a nice voltage slightly after the crash Voltage.

thats cool never thought does error codes. i just reset the pc everytime it crash. oh yeah one thing can i reduce the rpm of my cooler fan its really annoying i have thermaltake frio with adjustble controller for the fans im running at 2100+rpm and its really making annoying sound i tried to set it to 1700 to 1800 rpm the noise blends with the case fans unlike the 2100+rpm do you guys think it is safe if i set the rpm to 1700 to 1800rpm?